Description
The (1) publickey_make_dss, (2) publickey_make_rsa, (3) signature_from_string, (4) ssh_do_sign, and (5) ssh_sign_session_id functions in keys.c in libssh before 0.5.3 free "an invalid pointer on an error path," which might allow remote attackers to cause a denial of service (crash) via unspecified vectors.
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 | libssh | 0.5.3-1 | — |
| Debian 13 | libssh | 0.5.3-1 | — |
| Debian 12 | libssh | 0.5.3-1 | — |
| Debian 6.0 | libssh | 0.4.5-3+squeeze1 | DSA-2577-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libssh | 0.7.2-2.1 | openSUSE-SU-2024:10036-1 |
Advisories 2
- DSA-2577-1 libssh - several Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10036-1 libssh-devel-0.7.2-2.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- DSA-2577 vendor-advisory
- MDVSA-2012:175 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=871617
- USN-1640-1 vendor-advisory
- openSUSE-SU-2013:0130 vendor-advisory
- openSUSE-SU-2012:1622 vendor-advisory
- FEDORA-2012-18610 vendor-advisory
- openSUSE-SU-2012:1620 vendor-advisory
- [oss-security] 20121120 libssh 0.5.3 release fixes multiple security issues mailing-list
- libssh-multiple-dos(80220) vdb-entry
- FEDORA-2012-18677 vendor-advisory
- 56604 vdb-entry
- http://www.libssh.org/2012/11/20/libssh-0-5-3-security-release/