Description
A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed TLS through 2.23.0 allows an attacker to recover secret key information. This affects CBC mode because of a computed time difference based on a padding length.
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 |
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 | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | mbedtls +2 | 2.16.8-r0 | — |
| Alpine v3.23 | mbedtls +1 | 2.16.8-r0 | — |
| Alpine v3.22 | mbedtls +1 | 2.16.8-r0 | — |
| Alpine v3.21 | mbedtls +1 | 2.16.8-r0 | — |
| Alpine v3.20 | mbedtls +1 | 2.16.8-r0 | — |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.18 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.17 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.16 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.15 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.14 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.13 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.12 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.11 | mbedtls | 2.16.8-r0 | — |
| Alpine v3.10 | mbedtls | 2.16.8-r0 | — |
Advisories 1
- DLA-3249-1 mbedtls - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- https://tls.mbed.org/tech-updates/security-advisories
- https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2020-09-1
- FEDORA-2020-48a1ae610c vendor-advisory
- FEDORA-2020-8b0d59bac6 vendor-advisory
- FEDORA-2020-e75ade5e38 vendor-advisory
- [debian-lts-announce] 20221225 [SECURITY] [DLA 3249-1] mbedtls security update mailing-list