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Full vulnerability report · 2026
CVE-2026-59903High confidence

Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite

netty · netty

Official source article: GitHub GHSA-8C42-7QJ2-3J46 ↗. Check the applicable product and release in the original source.

6.5MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 132 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.25% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs netty netty and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 132 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 4 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appsnettyUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Open-source package ranges4 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
Mavenio.netty:netty-codec-httpECOSYSTEM: introduced 4.2.0.Final; fixed 4.2.17.Final4.2.17.FinalOSV record ↗aggregator derived · 10 Sep 2026
Mavenio.netty:netty-codec-httpECOSYSTEM: introduced 0; fixed 4.1.137.Final4.1.137.FinalOSV record ↗aggregator derived · 10 Sep 2026
mavenio.netty:netty-codec-http>= 4.2.0.Final, <= 4.2.16.Final4.2.17.FinalGitHub advisory ↗upstream repository advisory · 17 Aug 2026
mavenio.netty:netty-codec-http<= 4.1.136.Final4.1.137.FinalGitHub advisory ↗upstream repository advisory · 17 Aug 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-59903 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityio.netty/netty: Netty: Information disclosure via CORS Vary header overwrite
128 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • ceph-base as a component of Red Hat Ceph Storage 6
  • ceph-common as a component of Red Hat Ceph Storage 6
  • ceph-fuse as a component of Red Hat Ceph Storage 6
  • ceph-immutable-object-cache as a component of Red Hat Ceph Storage 6
  • ceph-mib as a component of Red Hat Ceph Storage 6
  • ceph-resource-agents as a component of Red Hat Ceph Storage 6
  • ceph-selinux as a component of Red Hat Ceph Storage 6
  • ceph.src as a component of Red Hat Ceph Storage 6
  • cephadm as a component of Red Hat Ceph Storage 6
  • cephfs-top as a component of Red Hat Ceph Storage 6
  • libcephfs-devel as a component of Red Hat Ceph Storage 6
  • libcephfs2 as a component of Red Hat Ceph Storage 6
Summary
A flaw was found in Netty, an asynchronous, event-driven network application framework. The `CorsHandler` component incorrectly replaces application `Vary` headers, such as `Authorization` or `Cookie`, with `Origin`. This allows a caching proxy or Content Delivery Network (CDN) to reuse authenticated responses across different users, leading to the disclosure of sensitive information.
Remediation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-60318

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 132 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse authenticated responses across users and disclose sensitive information. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

What

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse authenticated responses across users and disclose sensitive information. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

Why

The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.

What

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse authenticated responses across users and disclose sensitive information. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

Why

The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Use of Cache Containing Sensitive Information → obtain information outside the intended access boundary
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-524 ↗

CWE-524: Use of Cache Containing Sensitive Information. The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-524
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2026-2712Netty: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, und um Informationen offenzulegen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1249Multiples vulnérabilités dans les produits VMware

ord?id=CVE-2026-58043 Référence CVE CVE-2026-58055 https://www.cve.org/CVERecord?id=CVE-2026-58055 Référence CVE CVE-2026-59084 https://www.cve.org/CVERecord?id=CVE-2026-59084 Référence CVE CVE-2026-5928 https://www.cve.org/CVERecord?id=CVE-2026-5928 Référence CVE CVE-2026-59884 https://www.cve.org/CVERecord?id=CVE-2026-59884 Référence CVE CVE-2026-59885 https://www.cve.org/CVERecord?id=CVE-2026-59885 Référence CVE CVE-2026-59886 https://www.cve.org/CVERecord?id=CVE-2026-59886 Référence CVE CVE-2026-59889 https://www.cve.org/CVERecord?id=CVE-2026-59889 Référence CVE CVE-2026-59890 https://www.cve.org/CVERecord?id=CVE-2026-59890 Référence CVE CVE-2026-59903 https://www.cve.org/CVERecord?id=CVE-2026-59903 Référence CVE CVE-2026-6238 https://www.cve.org/CVERecord?id=CVE-2026-6238 Référence CVE CVE-2026-63072 https://www.cve.org/CVERecord?id=CVE-2026-63072 Référence CVE CVE-2026-63073 https://www.cve.org/CVERecord?id=CVE-2026-63073 Référence CVE CVE-2026-63074 https://www.cve.org/CVERecord?id=CVE-2026-63074 Référence CVE CVE-2026-63075 https://www.cve.org/CVERecord?id=CVE-2026-63075 Référence CVE CVE-2026-63076 https://www.cve.org/CVERecord?id=CVE-2026-63076 Référence CVE CVE-2026-63374 https://www.cve.org/CVERecord?id=CVE-2026-63374 Référence CVE CVE-2026-63379 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1165Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-59879 Référence CVE CVE-2026-59880 https://www.cve.org/CVERecord?id=CVE-2026-59880 Référence CVE CVE-2026-59888 https://www.cve.org/CVERecord?id=CVE-2026-59888 Référence CVE CVE-2026-59889 https://www.cve.org/CVERecord?id=CVE-2026-59889 Référence CVE CVE-2026-59893 https://www.cve.org/CVERecord?id=CVE-2026-59893 Référence CVE CVE-2026-59894 https://www.cve.org/CVERecord?id=CVE-2026-59894 Référence CVE CVE-2026-59898 https://www.cve.org/CVERecord?id=CVE-2026-59898 Référence CVE CVE-2026-59899 https://www.cve.org/CVERecord?id=CVE-2026-59899 Référence CVE CVE-2026-59901 https://www.cve.org/CVERecord?id=CVE-2026-59901 Référence CVE CVE-2026-59903 https://www.cve.org/CVERecord?id=CVE-2026-59903 Référence CVE CVE-2026-59921 https://www.cve.org/CVERecord?id=CVE-2026-59921 Référence CVE CVE-2026-60147 https://www.cve.org/CVERecord?id=CVE-2026-60147 Référence CVE CVE-2026-6051 https://www.cve.org/CVERecord?id=CVE-2026-6051 Référence CVE CVE-2026-6052 https://www.cve.org/CVERecord?id=CVE-2026-6052 Référence CVE CVE-2026-6053 https://www.cve.org/CVERecord?id=CVE-2026-6053 Référence CVE CVE-2026-60589 https://www.cve.org/CVERecord?id=CVE-2026-60589 Référence CVE CVE-2026-61308 https://www.cve.org/CVERecord?id=CVE-2026-61308 Référence CVE CVE-2026-62243 https://www.cve.org/CVERecord?id=CVE-20

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-035169Nettyにおける重要な情報を含むキャッシュの使用に関する脆弱性

Nettyは非同期でイベント駆動型のネットワークアプリケーションフレームワークです。4.1.137.Finalおよび4.2.17.Finalより前のバージョンでは、io.netty.handler.codec.http.cors.CorsHandlerのsetVaryHeaderがAuthorizationやCookieといったアプリケーションのVaryヘッダーをOriginに置き換えてしまいました。そのため、キャッシュプロキシやCDNが認証済みのレスポンスをユーザー間で再利用し、機密情報が漏洩する可能性がありました。この問題はバージョン4.1.137.Finalおよび4.2.17.Finalで修正されています。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official vendor articles3 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

04

Evidence and provenance

Published 17 Aug 2026 · Last source change 17 Aug 2026, 18:14 UTC · CWE-524 · Use of Cache Containing Sensitive Information

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-23
European sourceENISA EUVD · EUVD-2026-60318
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    netty-codec-http as a component of Red Hat build of Quarkus; ceph-base as a component of Red Hat Ceph Storage 6; ceph-common as a component of Red Hat Ceph Storage 6; ceph-fuse as a component of Red Hat Ceph Storage 6; ceph-immutable-object-cache as a component of Red Hat Ceph Storage 6; ceph-mib as a component of Red Hat Ceph Storage 6; ceph-resource-agents as a component of Red Hat Ceph Storage 6; ceph-selinux as a component of Red Hat Ceph Storage 6; ceph.src as a component of Red Hat Ceph Storage 6; cephadm as a component of Red Hat Ceph Storage 6; cephfs-top as a component of Red Hat Ceph Storage 6; libcephfs-devel as a component of Red Hat Ceph Storage 6; libcephfs2 as a component of Red Hat Ceph Storage 6; librados-devel as a component of Red Hat Ceph Storage 6; librados2 as a component of Red Hat Ceph Storage 6; libradospp-devel as a component of Red Hat Ceph Storage 6; libradosstriper1 as a component of Red Hat Ceph Storage 6; librbd-devel as a component of Red Hat Ceph Storage 6; librbd1 as a component of Red Hat Ceph Storage 6; librgw-devel as a component of Red Hat Ceph Storage 6; librgw2 as a component of Red Hat Ceph Storage 6; python3-ceph-argparse as a component of Red Hat Ceph Storage 6; python3-ceph-common as a component of Red Hat Ceph Storage 6; python3-cephfs as a component of Red Hat Ceph Storage 6; python3-rados as a component of Red Hat Ceph Storage 6; python3-rbd as a component of Red Hat Ceph Storage 6; python3-rgw as a component of Red Hat Ceph Storage 6; rbd-nbd as a component of Red Hat Ceph Storage 6; ceph-base as a component of Red Hat Ceph Storage 7; ceph-common as a component of Red Hat Ceph Storage 7; and 99 more
    After
    ceph-base as a component of Red Hat Ceph Storage 6; ceph-common as a component of Red Hat Ceph Storage 6; ceph-fuse as a component of Red Hat Ceph Storage 6; ceph-immutable-object-cache as a component of Red Hat Ceph Storage 6; ceph-mib as a component of Red Hat Ceph Storage 6; ceph-resource-agents as a component of Red Hat Ceph Storage 6; ceph-selinux as a component of Red Hat Ceph Storage 6; ceph.src as a component of Red Hat Ceph Storage 6; cephadm as a component of Red Hat Ceph Storage 6; cephfs-top as a component of Red Hat Ceph Storage 6; libcephfs-devel as a component of Red Hat Ceph Storage 6; libcephfs2 as a component of Red Hat Ceph Storage 6; librados-devel as a component of Red Hat Ceph Storage 6; librados2 as a component of Red Hat Ceph Storage 6; libradospp-devel as a component of Red Hat Ceph Storage 6; libradosstriper1 as a component of Red Hat Ceph Storage 6; librbd-devel as a component of Red Hat Ceph Storage 6; librbd1 as a component of Red Hat Ceph Storage 6; librgw-devel as a component of Red Hat Ceph Storage 6; librgw2 as a component of Red Hat Ceph Storage 6; python3-ceph-argparse as a component of Red Hat Ceph Storage 6; python3-ceph-common as a component of Red Hat Ceph Storage 6; python3-cephfs as a component of Red Hat Ceph Storage 6; python3-rados as a component of Red Hat Ceph Storage 6; python3-rbd as a component of Red Hat Ceph Storage 6; python3-rgw as a component of Red Hat Ceph Storage 6; rbd-nbd as a component of Red Hat Ceph Storage 6; ceph-base as a component of Red Hat Ceph Storage 7; ceph-common as a component of Red Hat Ceph Storage 7; ceph-fuse as a component of Red Hat Ceph Storage 7; and 98 more
    Red Hat Product Security ↗
  2. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added patch: github.com/17213; added patch: github.com/17217; 2 further additions.
    Before
    no authoritative guidance recorded
    After
    patch: github.com/17213 · patch: github.com/17217 · remediation: github.com/17213 · 1 more references
    security-advisories@github.com ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    < 4.1.137.Final; >= 4.2.0.Final, < 4.2.17.Final · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    netty: < 4.1.137.Final, >= 4.2.0.Final, < 4.2.17.Final · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
  5. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    security-advisories@github.com ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-60318↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference · GitHub GHSA-8C42-7QJ2-3J46↗Patch or update reference↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-59903 · cve.blacktree.nl