CVE-2026-6669 Unbounded SCRAM iteration count causes CPU exhaustion in PgBouncer
A malicious PostgreSQL backend can cause CPU exhaustion in PgBouncer by sending an unbounded SCRAM iteration count, disrupting service for all clients.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-6669?
CVE-2026-6669 is a medium-severity denial of service vulnerability in PgBouncer, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Missing upper bound on the key derivation iteration count accepted during SCRAM authentication to a backend server in PgBouncer through 1.25.2 allows a malicious or compromised PostgreSQL backend to cause uncontrolled CPU consumption in PgBouncer. The resulting key derivation cannot be interrupted in frontend builds such as PgBouncer. Because PgBouncer serves all clients from a single process, one backend can in this way stop it from serving traffic for every other database and client it is pooling, so the failure of a single backend is not contained.
Weakness: CWE-400
Which versions are affected by CVE-2026-6669?
1 open source package ship an affected version, including pgbouncer.
| Package | Affected | Fixed in |
|---|---|---|
pgbouncer Bitnami | All versions | 1.26.0 |
How do I fix CVE-2026-6669?
Upgrade pgbouncer to 1.26.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-6669 being exploited?
There is no known exploitation of CVE-2026-6669 in the wild and no public exploit code.
Sources
Also known as AZL-105063, BIT-pgbouncer-2026-6669, DEBIAN-CVE-2026-6669, ECHO-001a-32d5-11bc, GHSA-58j7-v2vx-r29w, MINI-hvw2-c96x-c9r9 and 1 more.