CVE-2026-6665 PgBouncer buffer overflow in SCRAM

High 8.1 Published 9 May 2026 Updated 12 May 2026

A malicious backend can trigger a stack overflow in PgBouncer's SCRAM implementation, potentially leading to code execution or denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-6665?

CVE-2026-6665 is a high-severity memory corruption vulnerability in PgBouncer, published on 9 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The SCRAM code in PgBouncer before 1.25.2 did not check the return value of strlcat() correctly when building the contents of the SCRAM client-final-message. A malicious backend that sends a SCRAM server-final-message with a long nonce can trigger a stack overflow.

Weakness: CWE-121

Which versions are affected by CVE-2026-6665?

1 open source package ship an affected version, including pgbouncer. It affects 1 product.

Package	Affected	Fixed in
`pgbouncer` Bitnami	All versions	`1.25.2`

Products include Pgbouncer Pgbouncer.

How do I fix CVE-2026-6665?

Upgrade pgbouncer to 1.25.2 or later.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-6665 being exploited?

There is no known exploitation of CVE-2026-6665 in the wild and no public exploit code.

Sources

Also known as AZL-86237, BIT-pgbouncer-2026-6665, CLEANSTART-2026-GK06303, DEBIAN-CVE-2026-6665, GHSA-mhmx-mjv6-w337, MINI-gmgh-r96c-fx35 and 1 more.