CVE-2026-6665: The SCRAM code in PgBouncer before 1.25.2 did not check the return value of strlcat() correctly when building

Q: How do I fix CVE-2026-6665?

pgbouncer: upgrade to 1.25.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-6665 being exploited?

CVE-2026-6665 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-6665 affect?

CVE-2026-6665 affects pgbouncer. Severity is high (CVSS 8.1). 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

Q: How urgent is CVE-2026-6665?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 8.1REMOTEUPGRADE

CVE-2026-6665 is a high-severity flaw (CVSS 8.1) affecting pgbouncer. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 69%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-05-09
Last modified	2026-07-24

Publisher (CNA): PostgreSQL · Vendor: pgbouncer

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-09 01:16 UTCPublished CVE record published
2026-07-24 08:10 UTCUpdated Record last modified

pgbouncer pgbouncer UPGRADE

Affected: < 1.25.2

Fixed in: 1.25.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy pgbouncer || rpm -q pgbouncer || pgbouncer --version

2. UPGRADE to 1.25.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade pgbouncer

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade pgbouncer

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-6665?

pgbouncer: upgrade to 1.25.2. Exact commands for each OS are on this page.

Is CVE-2026-6665 being exploited?

CVE-2026-6665 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-2026-6665 affect?

CVE-2026-6665 affects pgbouncer. Severity is high (CVSS 8.1). 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

How urgent is CVE-2026-6665?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-6664 HIGH 7.5 UPGRADE An integer overflow in network packet parsing code in PgBouncer before 1.25.2 bypasses a boundary check and ca
CVE-2026-6666 MEDIUM 5.9 UPGRADE A possible null pointer reference in PgBouncer before 1.25.2 could lead to a crash, if a server sends an error
CVE-2026-6667 MEDIUM 4.3 UPGRADE PgBouncer before 1.25.2 did not perform an appropriate authorization check for the KILL_CLIENT admin command

References

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