CVE-2026-55164 Lemur: Plaintext password storage in Lemur user-update path
Administrators can store user passwords in plaintext, exposing credentials to database compromises and preventing normal authentication.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55164?
CVE-2026-55164 is a medium-severity vulnerability in Netflix lemur, published on 18 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Lemur manages TLS certificate creation. Prior to 1.9.2, lemur.users.service.update assigned a replacement password directly to users.password, while lemur/users/models.py registered User.hash_password only for the before_insert event. Because no before_update listener ran, administrator-initiated password changes through PUT /api/1/users/ were committed as plaintext. The affected user could no longer authenticate normally because bcrypt verification received an unhashed value. A database, backup, replica, query-log, or administrative read compromise exposed immediately usable credentials without offline cracking. The fix registers hashing for before_update and avoids rehashing values that already have a bcrypt prefix. This issue is fixed in version 1.9.2.
Weakness: CWE-256
Which versions are affected by CVE-2026-55164?
3 open source packages ship an affected version, including lemur.
| Package | Affected | Fixed in |
|---|---|---|
lemur PyPI | All versions | 1.9.2 |
lemur PyPI | All versions | 1.9.2 |
lemur PyPI | All versions | 1.9.2 |
How do I fix CVE-2026-55164?
Upgrade lemur to 1.9.2 or later.
Is CVE-2026-55164 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55164 exists.
Sources
Also known as GHSA-q437-g7fv-2jvv, PYSEC-2026-2587.