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TI-2026-27112 Aliases CVE-2026-34876GHSA-jw9g-6hxw-4whq

An issue was discovered in Mbed TLS 3.x before 3.6.6.

Priority LOW 39CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
No fix listed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.

Summary

An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00406 35th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:trustedfirmware:mbed_tls:*:*:*:*:*:*:*:*3.1.0 to before 3.6.6VulnerableOP-TEE
  • cpe:2.3:a:trustedfirmware:mbed_tls:*:*:*:*:*:*:*:* Versions 3.1.0 to before 3.6.6 Vulnerable ·OP-TEE

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34876
  2. 2026-10-03 Alias added: GHSA-jw9g-6hxw-4whq

References

Advisory 2

  • TI-2023-24211 Mbed TLS 3.2.x through 3.4.x before 3.5 has a Buffer Overflow that can lead to remote Code execution. CVSS 3.1CRITICAL 9.8
  • TI-2022-22925 An issue was discovered in Mbed TLS before 2.28.2 and 3.x before 3.3.0. CVSS 3.1CRITICAL 9.8
  • TI-2024-32797 Mbed TLS 3.5.x through 3.6.x before 3.6.2 has a buffer underrun in pkwrite when writing an opaque key pair CVSS 3.1CRITICAL 9.8
  • TI-2024-30255 An issue was discovered in Mbed TLS 3.6 before 3.6.1. CVSS 3.1CRITICAL 9.8
  • TI-2026-27113 An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. CVSS 3.1CRITICAL 9.8
  • TI-2026-27111 An issue was discovered in Mbed TLS through 3.6.5 and TF-PSA-Crypto 1.0.0. CVSS 3.1CRITICAL 9.8
See all 40 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences