CVE-2026-107348
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Integer Overflow in PgBouncer Leading to Denial of Service

Vulnerability report for CVE-2026-107348, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-14

Last updated on: 2026-10-16

Assigner: PostgreSQL

Description

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.

CVSS Scores

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Meta Information

Published
2026-10-14
Last Modified
2026-10-16
Generated
2026-10-19
AI Q&A
2026-10-15
EPSS Evaluated
2026-10-18
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
n/a PgBouncer 1.21.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
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.
CWE-835 The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Attack-Flow Graph

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Executive Summary

This vulnerability is an integer overflow in PgBouncer's message buffer growth logic (mbuf_make_room) affecting versions 1.21.0 through 1.26.0. When max_packet_size is set above 2147483648, a packet header declaring a length above 2^31 causes the buffer size computation to overflow. This makes the growth loop unable to terminate, leading to CPU saturation and denial of service for all pooled connections.

Detection Guidance

Detecting this vulnerability requires monitoring for abnormal CPU usage or stalled connections in PgBouncer. Check for processes consuming excessive CPU with commands like 'top' or 'htop'. Inspect PgBouncer logs for connection stalls or timeouts. Ensure max_packet_size is not set above 2147483648.

Impact Analysis

This vulnerability allows a remote attacker to cause a denial of service by sending a specially crafted packet. It saturates a CPU core and stalls every pooled connection until the PgBouncer process is restarted. Since 1.23.0, the overflow can be triggered before authentication with a five-byte packet header.

Compliance Impact

This vulnerability causes a denial of service by saturating CPU resources, which could lead to prolonged unavailability of database connections. For GDPR, this may impact data availability and processing rights. For HIPAA, it could disrupt access to protected health information, potentially violating access controls and availability requirements.

Mitigation Strategies

Upgrade PgBouncer to a version beyond 1.26.0 where the issue is fixed. If upgrading is not possible, set max_packet_size to 2147483648 or lower. Monitor network traffic for malformed packets with length headers above 2^31.

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