Integer overflow causes an infinite loop in message buffer growth in PgBouncer

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-107348
StatePUBLISHED
AssignerPostgreSQL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-14 18:17:25 UTC
Updated2026-10-16 21:17:18 UTC
DescriptionInteger 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from f86ef6dc-4d3a-42ad-8f28-e6d5547a5007

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-190 | CWE-835 | CWE-190 Integer Overflow or Wraparound | CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

VersionSourceTypeScoreSeverityVector
3.1f86ef6dc-4d3a-42ad-8f28-e6d5547a5007Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na PgBouncer affected 1.21.0 1.26.1 semver Not specified

References

ReferenceSourceLinkTags
www.pgbouncer.org/changelog.html f86ef6dc-4d3a-42ad-8f28-e6d5547a5007 www.pgbouncer.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Thanks to Brian Cosgrove (@cosgroveb) for finding and reporting this issue. (en)

Additional Advisory Data

Workarounds

CNA: Set max_packet_size to 2147483647 (the default) or lower.

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