Medium severity · published Apr 1, 2026
CVE-2026-25834
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade
6.5
CVSS
0.1%
EPSS
No
On KEV
Description
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 3% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MT
Mbed Tls · Trustedfirmware
3.3.0 before 3.6.6; 4.0.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25834
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-25834
Vendor Advisory
https://mbed-tls.readthedocs.io/en/latest/security-advisories/
Vendor Advisory
https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-sigalg-injection/
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