CVE-2026-6665
Received Received - Intake
SCRAM Stack Overflow in PgBouncer

Publication date: 2026-05-09

Last updated on: 2026-05-09

Assigner: PostgreSQL

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.
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Meta Information
Published
2026-05-09
Last Modified
2026-05-09
Generated
2026-06-19
AI Q&A
2026-05-09
EPSS Evaluated
2026-06-18
NVD
CVE-2026-6665
EUVD
EUVD-2026-28877
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
pgbouncer pgbouncer to 1.25.2 (exc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
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Executive Summary

The vulnerability exists in the SCRAM code of PgBouncer versions before 1.25.2. It occurs because the code did not correctly check the return value of the strlcat() function when constructing the SCRAM client-final-message. This flaw allows a malicious backend to send a specially crafted SCRAM server-final-message containing a long nonce, which can trigger a stack overflow.

Impact Analysis

This vulnerability can lead to a stack overflow, which may allow an attacker to execute arbitrary code, cause a denial of service, or compromise the integrity and availability of the PgBouncer service. Given the CVSS score of 8.1, the impact includes high confidentiality, integrity, and availability risks.

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