Description
An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | mbedtls | 2.16.9-0.1 | — |
| Debian 13 | mbedtls | 2.16.9-0.1 | — |
| Debian 12 | mbedtls | 2.16.9-0.1 | — |
| Debian 10 | mbedtls | 2.16.9-0~deb10u1 | DLA-3249-1 |
| Debian 9 | mbedtls | 2.4.2-1+deb9u4 | DLA-2826-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | mbedtls | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | mbedtls | No fix yet | — |
| Ubuntu Pro 18.04 LTS | mbedtls | No fix yet | — |
Advisories 4
- DLA-3249-1 mbedtls - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2826-1 mbedtls - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SSA-756638 SSA-756638: Vulnerabilities in Third-Party Component Mbed TLS of LOGO! CMR Family and SIMATIC RTU 3000 Family Siemens ProductCERT · May 10, 2022
- ICSA-21-257-20 Siemens LOGO! CMR and SIMATIC RTU 3000 CISA ICS & IT advisories · Sep 14, 2021
References
- https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0
- https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9
- https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18
- https://github.com/ARMmbed/mbedtls/issues/3629
- https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf
- [debian-lts-announce] 20211123 [SECURITY] [DLA 2826-1] mbedtls security update mailing-list
- [debian-lts-announce] 20221225 [SECURITY] [DLA 3249-1] mbedtls security update mailing-list