Unbounded SCRAM iteration count causes CPU exhaustion in PgBouncer

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-6669
StatePUBLISHED
AssignerPostgreSQL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-23 17:17:16 UTC
Updated2026-09-23 19:40:10 UTC
DescriptionMissing 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from f86ef6dc-4d3a-42ad-8f28-e6d5547a5007

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003140000 probability, percentile 0.216170000 (date 2026-09-24)

Problem Types: CWE-400 | CWE-400 Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
3.1f86ef6dc-4d3a-42ad-8f28-e6d5547a5007Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na PgBouncer affected 1.25.2 semver Not specified

References

ReferenceSourceLinkTags
www.pgbouncer.org/changelog.html f86ef6dc-4d3a-42ad-8f28-e6d5547a5007 www.pgbouncer.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Thanks to @HarutoKimura for finding and reporting this issue. (en)

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