---
id: CVE-2026-107348
title: >-
  Integer overflow in the message buffer growth logic (mbuf_make_room) in
  PgBouncer 1.21.0 through 1.26.0 allows a remote attacker to cause a denial of
  service when max_packet_size is configured above 2147483648
summary: >-
  Integer overflow in the message buffer growth logic (mbuf_make_room) in
  PgBouncer 1.21.0 through 1.26.0 allows a remote attacker to cause a denial of
  service when max_packet_size is configured above 2147483648. A packet header
  declaring …
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-190
  - CWE-835
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T18:17:25.430'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107348'
references:
  - url: 'https://www.pgbouncer.org/changelog.html'
    label: f86ef6dc-4d3a-42ad-8f28-e6d5547a5007
tags:
  - nvd
ingestedAt: '2026-10-14T18:47:39.309Z'
---

## Overview

Integer overflow in the message buffer growth logic (mbuf_make_room) in PgBouncer 1.21.0 through 1.26.0 allows a remote attacker to cause a denial of service when max_packet_size is configured above 2147483648. A packet header declaring a length above 2^31 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 restarted. Since 1.23.0 the overflow is reachable before authentication with a five-byte packet header.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.