PgBouncer up to 1.25.1 strlcat stack-based overflow

CVSS Meta Temp Score
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CTI Interest Score
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7.8$0-$5k0.00

Summaryinfo

A vulnerability was found in PgBouncer up to 1.25.1. It has been classified as critical. This affects the function strlcat. The manipulation leads to stack-based overflow. This vulnerability is documented as CVE-2026-6665. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in PgBouncer up to 1.25.1 and classified as critical. This issue affects the function strlcat. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to 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). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was released by Haruto Kimura. The advisory is shared at pgbouncer.org. The identification of this vulnerability is CVE-2026-6665 since 04/20/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 313598 (Linux Distros Unpatched Vulnerability : CVE-2026-6665), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.25.2 eliminates this vulnerability. The upgrade is hosted for download at pgbouncer.org.

The vulnerability is also documented in the databases at Tenable (313598) and CERT Bund (WID-SEC-2026-1445). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Microsoft Azure Linux
  • Open Source PgBouncer

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.8
VulDB Meta Temp Score: 7.8

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CNA Base Score: 8.1
CNA Vector (PostgreSQL): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 313598
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-6665

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: PgBouncer 1.25.2

Timelineinfo

04/20/2026 CVE reserved
05/09/2026 +19 days Advisory disclosed
05/09/2026 +0 days VulDB entry created
05/18/2026 +9 days VulDB entry last update

Sourcesinfo

Advisory: pgbouncer.org
Researcher: Haruto Kimura
Status: Confirmed

CVE: CVE-2026-6665 (🔒)
GCVE (CVE): GCVE-0-2026-6665
GCVE (VulDB): GCVE-100-362381
CERT Bund: WID-SEC-2026-1445 - PgBouncer: Mehrere Schwachstellen

Entryinfo

Created: 05/09/2026 06:54
Updated: 05/18/2026 11:39
Changes: 05/09/2026 06:54 (65), 05/10/2026 01:13 (2), 05/13/2026 02:30 (7), 05/18/2026 11:39 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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