Description
SSH, as implemented in OpenSSH before 4.0 and possibly other implementations, stores hostnames, IP addresses, and keys in plaintext in the known_hosts file, which makes it easier for an attacker that has compromised an SSH user's account to generate a list of additional targets that are more likely to have the same password or key.
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 | openssh | 1:4.0p1-1 | — |
| Debian 13 | openssh | 1:4.0p1-1 | — |
| Debian 12 | openssh | 1:4.0p1-1 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 4 | openssh +4 | 3.9p1-8.RHEL4.20 | RHSA-2007:0257 |
Advisories 1
- RHSA-2007:0257 Red Hat Security Advisory: openssh security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
References
- oval:org.mitre.oval:def:10201 vdb-entry signature
- 25098 third-party-advisory
- RHSA-2007:0257 vendor-advisory
- 19243 third-party-advisory
- http://www.eweek.com/article2/0%2C1759%2C1815795%2C00.asp
- http://nms.csail.mit.edu/projects/ssh/