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Full vulnerability report · 2026
CVE-2026-78161High confidence

warmcat libwebsockets LECP CBOR Recording lecp.c report_raw_cbor out-of-bounds write

warmcat · libwebsockets

6.9MediumCVSS 4.0
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 24 Aug 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.40% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs warmcat libwebsockets 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: Within 30 daysRemediation target: Within 180 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.

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
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 · sourcelibwebsocketsVendor fix publishedDebian records a fixed source-package version for this release.4.3.5-1+deb13u2Debian Security Tracker ↗Source updated 7 Oct 2026
Debian bookwormbookworm · sourcelibwebsocketsNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 7 Oct 2026
Debian forkyforky · sourcelibwebsocketsVendor fix publishedDebian records a fixed source-package version for this release.4.3.5-6Debian Security Tracker ↗Source updated 7 Oct 2026
Debian sidsid · sourcelibwebsocketsVendor fix publishedDebian records a fixed source-package version for this release.4.3.5-6Debian Security Tracker ↗Source updated 7 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appslibwebsocketsVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.4.3.3-1.1ubuntu0.1~esm2Canonical Ubuntu Security ↗Source updated 6 Oct 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-2026-78161 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibwebsockets: libwebsockets: Out-of-bounds write in LECP CBOR Recording
7 known not affected

The vendor explicitly states that these products are not affected by this CVE.

  • libwebsockets.src as a component of A-MQ Interconnect 1
  • libwebsockets.src as a component of Red Hat OpenStack Platform 16.2
  • libwebsockets as a component of Red Hat OpenStack Platform 17.1
  • libwebsockets.src as a component of Red Hat OpenStack Platform 17.1
  • libwebsockets as a component of Red Hat Satellite 6
  • libwebsockets.src as a component of Red Hat Satellite 6
  • libwebsockets.src as a component of Red Hat Service Interconnect 2
Summary
A flaw was found in warmcat libwebsockets. A remote attacker could exploit an out-of-bounds write vulnerability in the LECP CBOR Recording component, specifically within the `report_raw_cbor` function. This could lead to information disclosure, data corruption, or denial of service.
Remediation
No remediation text is recorded.
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-2026-64685

No EUVD known-exploited evidence

A vulnerability was found in warmcat libwebsockets 4.5.0. Impacted is the function report_raw_cbor of the file lib/misc/lecp.c of the component LECP CBOR Recording. The manipulation results in out-of-bounds write. The attack can be launched remotely. The exploit has been made public and could be used. The patch is identified as 1d44554a1bb262db63ff4e240152a9deecd99054. It is best practice to apply a patch to resolve this issue.

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
6.9 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

A vulnerability was found in warmcat libwebsockets 4.5.0. Impacted is the function report_raw_cbor of the file lib/misc/lecp.c of the component LECP CBOR Recording. The manipulation results in out-of-bounds write. The attack can be launched remotely. The exploit has been made public and could be used. The patch is identified as 1d44554a1bb262db63ff4e240152a9deecd99054. It is best practice to apply a patch to resolve this issue.

What

A vulnerability was found in warmcat libwebsockets 4.5.0. Impacted is the function report_raw_cbor of the file lib/misc/lecp.c of the component LECP CBOR Recording. The manipulation results in out-of-bounds write. The attack can be launched remotely. The exploit has been made public and could be used. The patch is identified as 1d44554a1bb262db63ff4e240152a9deecd99054. It is best practice to apply a patch to resolve this issue.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

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

A vulnerability was found in warmcat libwebsockets 4.5.0. Impacted is the function report_raw_cbor of the file lib/misc/lecp.c of the component LECP CBOR Recording. The manipulation results in out-of-bounds write. The attack can be launched remotely. The exploit has been made public and could be used. The patch is identified as 1d44554a1bb262db63ff4e240152a9deecd99054. It is best practice to apply a patch to resolve this issue.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

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.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
a network path → Out-of-bounds Write → 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
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-787 ↗

CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCLowVulnerable-system confidentiality: A successful attack can cause a limited loss.VILowVulnerable-system integrity: A successful attack can cause a limited loss.VALowVulnerable-system availability: A successful attack can cause a limited loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: 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-787Public exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-64685Official EUVD mapping

A vulnerability was found in warmcat libwebsockets 4.5.0. Impacted is the function report_raw_cbor of the file lib/misc/lecp.c of the component LECP CBOR Recording. The manipulation results in out-of-bounds write. The attack can be launched remotely. The exploit has been made public and could be used. The patch is identified as 1d44554a1bb262db63ff4e240152a9deecd99054. It is best practice to apply a patch to resolve this issue.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260826Security Bulletin 26 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Aug 2026, published on 26 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

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.
Patch available
Affected
libwebsockets: 4.5.0
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
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 24 Aug 2026 · Last source change 24 Aug 2026, 17:22 UTC · CWE-787 · Out-of-bounds Write

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 2026-08-24
European sourceENISA EUVD · EUVD-2026-64685
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  2. ENISA EUVD mappingEUVD-2026-64685 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-64685"}
    ENISA EUVD ↗
  3. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-64685↗Vendor CSAF · Red Hat Product Security↗CISA Vulnrichment SSVC evidence↗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-2026-78161 · cve.blacktree.nl