🛡️ CVE-2025-27809 — mbed-tls

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

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

• Attack vector: Network — reachable from anywhere that can route to the service.
• 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: Changed — a successful attack reaches components beyond the vulnerable one.
• Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
• Integrity impact: Low — limited, and the attacker does not choose what is affected.
• Availability impact: None.

Weakness class

CVE-2025-27809 is classified as CWE-1188: Insecure Default Initialization of Resource. Default settings are insecure, so an installation is exposed until someone changes them.

Affected software

CVE-2025-27809 is recorded against 1 package.

• mbed-tls (from 3.0.0 up to 3.6.3)

Timeline and source

Published on 25 March 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
mbed-tls.readthedocs.io
github.com
mastodon.social

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-2026-34876 (7.5 High, published 2 Apr 2026)
• CVE-2026-34877 (9.8 Critical, published 2 Apr 2026)
• CVE-2026-25835 (7.7 High, published 1 Apr 2026)
• CVE-2026-25834 (6.5 Medium, published 1 Apr 2026)
• CVE-2026-34875 (9.8 Critical, published 1 Apr 2026)
• CVE-2026-25833 (7.5 High, published 1 Apr 2026)
• CVE-2026-34874 (7.5 High, 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-1188: Insecure Default Initialization of Resource) in other software:

• CVE-2026-63563 (6.5 Medium, published 3 Aug 2026)
• CVE-2026-62416 (5.3 Medium, published 3 Aug 2026)
• CVE-2026-16503 (9.1 Critical, published 31 Jul 2026)
• CVE-2026-66066 (9.5 Critical, published 30 Jul 2026)
• CVE-2026-9680 (5.8 Medium, published 28 Jul 2026)
• CVE-2026-57147 (9.5 Critical, published 23 Jul 2026)
• CVE-2026-57127 (9.5 Critical, published 23 Jul 2026)
• CVE-2026-55708 (3.1 Low, published 22 Jul 2026)

CVE-2025-27809 on other distributions

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

Details

Affected Packages

References