CVE-2009-1273: pam_ssh 1.92 and possibly other versions, as used when PAM is compiled with USE=ssh, generates different error

Routine

MEDIUM 5.0DOWNGRADE

CVE-2009-1273 is a medium-severity flaw (CVSS 5.0) affecting pam ssh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

pam_ssh 1.92 and possibly other versions, as used when PAM is compiled with USE=ssh, generates different error messages depending on whether the username is valid or invalid, which makes it easier for remote attackers to enumerate usernames.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-255
Published	2009-04-08
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: andrew j.korty

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2009-04-08 18:30 UTCPublished CVE record published
2026-06-16 23:06 UTCUpdated Record last modified

andrew j.korty pam ssh DOWNGRADE

Affected: 1.92

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.92

1. Check installed version

apt-cache policy pam-ssh || rpm -q pam-ssh || pam-ssh --version

2. No fixed release: DOWNGRADE to a release before 1.92 (Debian / Ubuntu)

apt-cache madison pam-ssh sudo apt install pam-ssh=<VERSION_BEFORE_1.92> sudo apt-mark hold pam-ssh

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list pam-ssh sudo dnf downgrade pam-ssh-<VERSION_BEFORE_1.92> sudo dnf versionlock add pam-ssh

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2009-1273?

pam ssh: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2009-1273 being exploited?

CVE-2009-1273 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2009-1273 affect?

CVE-2009-1273 affects pam ssh. Severity is medium (CVSS 5.0). pam_ssh 1.92 and possibly other versions, as used when PAM is compiled with USE=ssh, generates different error messages depending on whether the username is valid or invalid, which makes it easier for remote attackers to enumerate usernames

How urgent is CVE-2009-1273?

Priority 35/100. No elevated risk signals yet.

References

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