CVE-2026-25834

unknown

Published — · Modified —

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

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Description

Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

Mitigation details

Source: Debian Security Tracker · View original ↗ · DFSG

CVE-2026-25834 NameCVE-2026-25834 DescriptionMbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade. SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) Debian Bugs1133841 Vulnerable and fixed packages The table below lists information on source packages. Source…

CVE-2026-25834

Name	CVE-2026-25834
Description	Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1133841

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
mbedtls (PTS)	bullseye	2.16.9-0.1	fixed
	bullseye (security)	2.16.9-0.1+deb11u4	fixed
	bookworm	2.28.3-1	fixed
	trixie	3.6.5-0.1~deb13u1	vulnerable
	forky, sid	3.6.6-0.1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Debian Bugs
mbedtls	source	bullseye	(not affected)
mbedtls	source	bookworm	(not affected)
mbedtls	source	(unstable)	3.6.6-0.1	1133841

Notes

[trixie] - mbedtls <no-dsa> (Minor issue)
[bookworm] - mbedtls <not-affected> (Vulnerable code introduced later)
[bullseye] - mbedtls <not-affected> (Vulnerable code introduced later)
https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection/
Introduced by: https://github.com/Mbed-TLS/mbedtls/commit/693a47ab1d076164baf0e5baff645b0e0d4d966b (mbedtls-3.3.0)
Fixed by: https://github.com/Mbed-TLS/mbedtls/commit/0165a8d7637a458f49cfe01be1f21aa0f91143d7 (mbedtls-3.6.6)

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Notes

[trixie] - mbedtls <no-dsa> (Minor issue)[bookworm] - mbedtls <not-affected> (Vulnerable code introduced later)[bullseye] - mbedtls <not-affected> (Vulnerable code introduced later)https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection/Introduced by: https://github.com/Mbed-TLS/mbedtls/commit/693a47ab1d076164baf0e5baff645b0e0d4d966b (mbedtls-3.3.0)Fixed by: https://github.com/Mbed-TLS/mbedtls/commit/0165a8d7637a458f49cfe01be1f21aa0f91143d7 (mbedtls-3.6.6)

OS impact

OS	Version	Status	Fixed in
sles		affected
debian	bookworm	fixed	`0`
debian	bullseye	fixed	`0`
debian	forky	fixed	`3.6.6-0.1`
debian	sid	fixed	`3.6.6-0.1`
debian	trixie	affected

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.