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Full vulnerability report · 2025
CVE-2025-6442High confidence

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability

Ruby · WEBrick

5.9MediumCVSS 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 92 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 0.50% 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 Ruby WEBrick 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 92 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 1 affected package state 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 · sourceruby-webrickVendor fix publishedDebian records a fixed source-package version for this release.1.9.1-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourceruby-webrickAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourceruby-webrickVendor fix publishedDebian records a fixed source-package version for this release.1.9.1-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourceruby-webrickVendor fix publishedDebian records a fixed source-package version for this release.1.9.1-1Debian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveruby-webrickVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.1.8.1-1ubuntu0.2Canonical Ubuntu Security ↗Source updated 5 Oct 2026
Open-source package ranges2 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
RubyGemswebrickECOSYSTEM: introduced 0; fixed 1.8.21.8.2OSV record ↗aggregator derived · 30 Jun 2025
rubygemswebrick< 1.8.21.8.2GitHub advisory ↗github reviewed aggregator · 30 Jun 2025
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-2025-6442 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitywebrick: Ruby WEBrick Request Smuggling Vulnerability
91 known affected

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

  • openshift-logging/fluentd-rhel8 as a component of Logging Subsystem for Red Hat OpenShift
  • openshift-logging/fluentd-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
  • openshift-service-mesh-dev-preview-beta/istio-ztunnel-rhel9 as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-cni-rhel9 as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-must-gather-rhel9 as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-pilot-rhel9 as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-proxyv2-rhel9 as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-rhel9-operator as a component of OpenShift Service Mesh 3
  • openshift-service-mesh/istio-sail-operator-bundle as a component of OpenShift Service Mesh 3
  • 3scale-amp2/zync-rhel8 as a component of Red Hat 3scale API Management Platform 2
  • 3scale-amp2/zync-rhel9 as a component of Red Hat 3scale API Management Platform 2
  • ruby as a component of Red Hat Enterprise Linux 6
Summary
A request smuggling vulnerability has been discovered in the Ruby WEBrick gem. This vulnerability is exploitable when the product is deployed behind a HTTP proxy that fulfills specific conditions.
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-2025-19113

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 92 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

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

What

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

Why

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

Why

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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 → Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') → cause the confidentiality, integrity or availability impact described by the vendor
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-444 ↗

CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'). The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

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:N/I:H/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.CNoneConfidentiality impact: No direct loss is represented by this metric.IHighIntegrity impact: A successful attack can cause a major 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-444
A

Official authority intelligence

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

BSI · German · WID-SEC-2025-2475Apple macOS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Apple macOS ausnutzen, um Informationen offenzulegen, um einen Denial of Service Angriff durchzuführen, um Sicherheitsvorkehrungen zu umgehen, um Dateien zu manipulieren, und um seine Privilegien zu erhöhen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20250702Security Bulletin 02 JUL 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 02 JUL 2025, published on 2 July 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0112Multiples vulnérabilités dans les produits VMware

d?id=CVE-2025-61594 Référence CVE CVE-2025-61723 https://www.cve.org/CVERecord?id=CVE-2025-61723 Référence CVE CVE-2025-61724 https://www.cve.org/CVERecord?id=CVE-2025-61724 Référence CVE CVE-2025-61725 https://www.cve.org/CVERecord?id=CVE-2025-61725 Référence CVE CVE-2025-61727 https://www.cve.org/CVERecord?id=CVE-2025-61727 Référence CVE CVE-2025-61729 https://www.cve.org/CVERecord?id=CVE-2025-61729 Référence CVE CVE-2025-61748 https://www.cve.org/CVERecord?id=CVE-2025-61748 Référence CVE CVE-2025-61795 https://www.cve.org/CVERecord?id=CVE-2025-61795 Référence CVE CVE-2025-61921 https://www.cve.org/CVERecord?id=CVE-2025-61921 Référence CVE CVE-2025-6442 https://www.cve.org/CVERecord?id=CVE-2025-6442 Référence CVE CVE-2025-64505 https://www.cve.org/CVERecord?id=CVE-2025-64505 Référence CVE CVE-2025-64506 https://www.cve.org/CVERecord?id=CVE-2025-64506 Référence CVE CVE-2025-64718 https://www.cve.org/CVERecord?id=CVE-2025-64718 Référence CVE CVE-2025-64720 https://www.cve.org/CVERecord?id=CVE-2025-64720 Référence CVE CVE-2025-65018 https://www.cve.org/CVERecord?id=CVE-2025-65018 Référence CVE CVE-2025-65637 https://www.cve.org/CVERecord?id=CVE-2025-65637 Référence CVE CVE-2025-65945 https://www.cve.org/CVERecord?id=CVE-2025-65945 Référence CVE CVE-2025-66418 https://www.cve.org/CVERecord?id=C

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-1131Multiples vulnérabilités dans les produits IBM

Record?id=CVE-2025-5914 Référence CVE CVE-2025-59250 https://www.cve.org/CVERecord?id=CVE-2025-59250 Référence CVE CVE-2025-59375 https://www.cve.org/CVERecord?id=CVE-2025-59375 Référence CVE CVE-2025-6020 https://www.cve.org/CVERecord?id=CVE-2025-6020 Référence CVE CVE-2025-61723 https://www.cve.org/CVERecord?id=CVE-2025-61723 Référence CVE CVE-2025-61725 https://www.cve.org/CVERecord?id=CVE-2025-61725 Référence CVE CVE-2025-61911 https://www.cve.org/CVERecord?id=CVE-2025-61911 Référence CVE CVE-2025-61912 https://www.cve.org/CVERecord?id=CVE-2025-61912 Référence CVE CVE-2025-6395 https://www.cve.org/CVERecord?id=CVE-2025-6395 Référence CVE CVE-2025-6442 https://www.cve.org/CVERecord?id=CVE-2025-6442 Référence CVE CVE-2025-6493 https://www.cve.org/CVERecord?id=CVE-2025-6493 Référence CVE CVE-2025-7962 https://www.cve.org/CVERecord?id=CVE-2025-7962 Référence CVE CVE-2025-8058 https://www.cve.org/CVERecord?id=CVE-2025-8058 Référence CVE CVE-2025-8941 https://www.cve.org/CVERecord?id=CVE-2025-8941 Gestion détaillée du document le 19 décembre 2025 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défe

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0961Multiples vulnérabilités dans les produits Apple

d?id=CVE-2025-43499 Référence CVE CVE-2025-43500 https://www.cve.org/CVERecord?id=CVE-2025-43500 Référence CVE CVE-2025-43502 https://www.cve.org/CVERecord?id=CVE-2025-43502 Référence CVE CVE-2025-43503 https://www.cve.org/CVERecord?id=CVE-2025-43503 Référence CVE CVE-2025-43504 https://www.cve.org/CVERecord?id=CVE-2025-43504 Référence CVE CVE-2025-43505 https://www.cve.org/CVERecord?id=CVE-2025-43505 Référence CVE CVE-2025-43506 https://www.cve.org/CVERecord?id=CVE-2025-43506 Référence CVE CVE-2025-43507 https://www.cve.org/CVERecord?id=CVE-2025-43507 Référence CVE CVE-2025-53906 https://www.cve.org/CVERecord?id=CVE-2025-53906 Référence CVE CVE-2025-6442 https://www.cve.org/CVERecord?id=CVE-2025-6442 Gestion détaillée du document le 04 novembre 2025 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes d'information

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0760Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2025-48050 Référence CVE CVE-2025-48068 https://www.cve.org/CVERecord?id=CVE-2025-48068 Référence CVE CVE-2025-48734 https://www.cve.org/CVERecord?id=CVE-2025-48734 Référence CVE CVE-2025-48976 https://www.cve.org/CVERecord?id=CVE-2025-48976 Référence CVE CVE-2025-50181 https://www.cve.org/CVERecord?id=CVE-2025-50181 Référence CVE CVE-2025-50182 https://www.cve.org/CVERecord?id=CVE-2025-50182 Référence CVE CVE-2025-52999 https://www.cve.org/CVERecord?id=CVE-2025-52999 Référence CVE CVE-2025-53547 https://www.cve.org/CVERecord?id=CVE-2025-53547 Référence CVE CVE-2025-5702 https://www.cve.org/CVERecord?id=CVE-2025-5702 Référence CVE CVE-2025-6442 https://www.cve.org/CVERecord?id=CVE-2025-6442 Référence CVE CVE-2025-7783 https://www.cve.org/CVERecord?id=CVE-2025-7783 Gestion détaillée du document le 05 septembre 2025 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes d'information

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2025-012181Ruby-lang.org の Ruby 用 Webrick における HTTP リクエストスマグリングに関する脆弱性

Ruby-lang.org の Ruby 用 Webrick には、HTTP リクエストスマグリングに関する脆弱性が存在します。

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0351Kwetsbaarheden verholpen in Apple MacOS

The Ruby WEBrick read_header HTTP Request Smuggling Vulnerability (CVE-2025-6442) allows remote attackers to exploit affected installations behind specific HTTP proxies, alongside userinfo leakage issues (CVE-2025-27221).

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 articles1 stored document

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.

  • About the security content of macOS Tahoe 26.1 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 29 Sep 2026Apple Store Mac iPad iPhone Watch Vision AirPods TV & Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","te
04

Evidence and provenance

Published 25 Jun 2025 · Last source change 25 Jun 2025, 20:42 UTC · CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-19113
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 ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

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-2025-19113↗Vendor CSAF · Red Hat Product Security↗Patch or update reference↗CVE authority or vendor 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-2025-6442 · cve.blacktree.nl