🛡️ CVE-2026-34871 — mbed-tls

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

• Attack vector: Local — a local account, shell or session on the host is needed.
• Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
• Privileges required: None — an unauthenticated stranger can try it.
• User interaction: None — nobody has to be tricked into anything.
• Scope: Unchanged — the damage stays inside the vulnerable component.
• Confidentiality impact: High — total loss, or loss the attacker controls.
• Integrity impact: High — total loss, or loss the attacker controls.
• Availability impact: None.

Weakness class

CVE-2026-34871 is classified as CWE-338: Use of Cryptographically Weak PRNG. A general-purpose random number generator is used where a cryptographic one is required.

Affected software

CVE-2026-34871 is recorded against 2 packages.

• mbed-tls (fixed in 3.6.6)
• tf-psa-crypto (fixed in 1.1.0)

Timeline and source

Published on 1 April 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

mbed-tls.readthedocs.io
mbed-tls.readthedocs.io

Other advisories for this package

mbed-tls has other advisories on record. If you are patching this one, these are worth checking on the same host:

• CVE-2026-34877 (9.8 Critical, published 2 Apr 2026)
• CVE-2026-34876 (7.5 High, published 2 Apr 2026)
• CVE-2026-34872 (9.1 Critical, published 1 Apr 2026)
• CVE-2026-25835 (7.7 High, published 1 Apr 2026)
• CVE-2026-25834 (6.5 Medium, published 1 Apr 2026)
• CVE-2026-25833 (7.5 High, published 1 Apr 2026)
• CVE-2026-34875 (9.8 Critical, published 1 Apr 2026)
• CVE-2025-66442 (5.1 Medium, published 1 Apr 2026)

Same weakness in other software

These advisories are the same class of weakness (CWE-338: Use of Cryptographically Weak PRNG) in other software:

• CVE-2026-18611 (7.5 High, published 10 Aug 2026)
• CVE-2026-9205 (7.4 High, published 5 Aug 2026)
• CVE-2026-47882 (8.3 High, published 30 Jul 2026)
• CVE-2026-16615 (6.8 Medium, published 22 Jul 2026)
• CVE-2026-64798 (9.1 Critical, published 22 Jul 2026)
• CVE-2026-16235 (9.8 Critical, published 20 Jul 2026)
• CVE-2026-8169 (published 20 Jul 2026)
• CVE-2026-13577 (8.2 High, published 20 Jul 2026)

CVE-2026-34871 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Affected Packages

References