CVE-2025-59438

Published Oct 21, 2025

Last updated 6 months ago

CVSS medium 5.3

Overview

Description: Mbed TLS through 3.6.4 has an Observable Timing Discrepancy.
Source: cve@mitre.org
NVD status: Analyzed
Products: mbed_tls

Risk scores

CVSS 3.1

Type: Secondary
Base score: 5.3
Impact score: 1.4
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Severity: MEDIUM

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0: CWE-208

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "D9DA7861-39B5-40B3-BF4F-6A79ED188844",
            "versionEndExcluding": "3.6.5",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.•CVE-2026-34877
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.•CVE-2026-34876
An issue was discovered in Mbed TLS 3.5.0 through 4.0.0. Client impersonation can occur while resuming a TLS 1.3 session.•CVE-2026-34873
An issue was discovered in Mbed TLS 3.5.x and 3.6.x through 3.6.5 and TF-PSA-Crypto 1.0. There is a lack of contributory behavior in FFDH due to improper input validation. Using finite-field Diffie-Hellman, the other party can force the shared secret into a small set of values (lack of contributory behavior). This is a problem for protocols that depend on contributory behavior (which is not the case for TLS). The attack can be carried by the peer, or depending on the protocol by an active network attacker (person in the middle).•CVE-2026-34872
In Mbed TLS through 4.0.0, there is a compiler-induced timing side channel (in RSA and CBC/ECB decryption) that only occurs with LLVM's select-optimize feature. TF-PSA-Crypto through 1.0.0 is also affected.•CVE-2025-66442

References

Sources include official advisories and independent security research.

https://nvd.nist.gov/vuln/detail/CVE-2025-59438
https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-10-invalid-padding-error/
https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/

Overview

Risk scores

CVSS 3.1

Weaknesses

Social media

Configurations

Related CVEs

References