CVE-2026-6668
Received Received - Intake

Integer Overflow in PgBouncer Leads to DoS

Vulnerability report for CVE-2026-6668, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-23

Last updated on: 2026-09-23

Assigner: PostgreSQL

Description

Integer overflow in the packet buffer growth logic in PgBouncer through 1.25.2 allows an unauthenticated remote attacker to cause a denial of service. Sufficiently large input makes the buffer size computation overflow, leaving the growth loop unable to terminate. Because PgBouncer serves all clients from a single process, this saturates a CPU core and stalls every pooled connection until the process is killed. Both unauthenticated and authenticated code paths can reach the overflow.

CVSS Scores

EPSS Scores

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Meta Information

Published
2026-09-23
Last Modified
2026-09-23
Generated
2026-09-23
AI Q&A
2026-09-23
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
pgbouncer pgbouncer 1.25.2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-835 The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
CWE-190 The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

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Executive Summary

Integer overflow in PgBouncer through 1.25.2 causes a denial of service. Large input leads to buffer size computation overflow, preventing the growth loop from terminating. This saturates a CPU core and stalls all pooled connections until the process is killed.

Detection Guidance

This vulnerability causes high CPU usage and stalled connections in PgBouncer. Monitor for processes consuming excessive CPU or unresponsive connections. Check PgBouncer logs for unusual packet sizes or errors during buffer growth. Use system tools like 'top', 'htop', or 'ps' to identify high CPU usage by PgBouncer.

Impact Analysis

This vulnerability allows an unauthenticated remote attacker to crash PgBouncer by sending specially crafted input, disrupting database connectivity for all users. It can lead to service unavailability and potential data access issues.

Mitigation Strategies

Upgrade PgBouncer to version 1.25.3 or later to patch the integer overflow issue. If immediate upgrade is not possible, restrict network access to PgBouncer using firewalls or disable pooling temporarily. Monitor CPU usage and restart PgBouncer if high CPU or stalled connections are detected.

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