CVE catalog

CVE-2026-86143

In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling

[CVE catalog]

Severity: Medium · CVSS 6.9CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
Published: Sep 5, 2026, 4:31:21 AM UTC
Updated: Sep 5, 2026, 5:17:13 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.19% · Oct 25, 2026

In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling writecallback. This has security relevance for many types of uses of that length value within a callback.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	libxml2	sid	`2.15.4+dfsg-1`	fixed
Debian	libxml2	forky	`2.15.4+dfsg-1`	fixed
Debian	libxml2	trixie	`2.12.7+dfsg+really2.9.14-2.1+deb13u3`	vulnerable
Debian	libxml2	trixie-security	`2.12.7+dfsg+really2.9.14-2.1+deb13u1`	vulnerable
Debian	libxml2	bookworm	`2.9.14+dfsg-1.3~deb12u6`	vulnerable
Debian	libxml2	bookworm-security	`2.9.14+dfsg-1.3~deb12u4`	vulnerable
Cpe	libxml2	Not reported	`2.15.4`	fixed
Ubuntu	libxml2	noble	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	libxml2-dev	noble	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	libxml2-doc	noble	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	libxml2-utils	noble	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	python3-libxml2	noble	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	libxml2	pro	`2.9.4+dfsg1-7ubuntu3`	vulnerable
Ubuntu	libxml2	pro	`2.9.4+dfsg1-7ubuntu5`	vulnerable
Ubuntu	libxml2	pro	`2.9.4+dfsg1-8ubuntu1`	vulnerable
Ubuntu	libxml2	pro	`2.9.4+dfsg1-8ubuntu2`	vulnerable
Ubuntu	libxml2	pro	`2.9.4+dfsg1-8ubuntu3`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-1ubuntu3`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-4build1`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.1`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.2`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.3`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.4`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.5`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.6`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.7`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.8`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.9`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm1`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm2`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm3`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm4`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm5`	vulnerable
Ubuntu	libxml2	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm6`	fixed
Ubuntu	libxml2	22.04	`2.9.12+dfsg-4`	vulnerable
Ubuntu	libxml2	22.04	`2.9.12+dfsg-5`	vulnerable
Ubuntu	libxml2	22.04	`2.9.12+dfsg-6`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1build1`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.1`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.2`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.3`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.4`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.5`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.6`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.7`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.8`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.9`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.10`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.11`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.12`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.13`	vulnerable
Ubuntu	libxml2	22.04	`2.9.13+dfsg-1ubuntu0.14`	fixed
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3build1`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3build2`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3build3`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu1`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu2`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.1`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.2`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.3`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.4`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.5`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.6`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.7`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.8`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.9`	vulnerable
Ubuntu	libxml2	24.04	`2.9.14+dfsg-1.3ubuntu3.10`	fixed
Ubuntu	libxml2	26.04	`2.14.5+dfsg-0.2`	vulnerable
Ubuntu	libxml2	26.04	`2.14.5+dfsg-0.2build1`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-0.3`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-0.4`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-1`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-2`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-2ubuntu1`	vulnerable
Ubuntu	libxml2	26.04	`2.15.1+dfsg-2ubuntu2`	vulnerable
Ubuntu	libxml2	26.04	`2.15.2+dfsg-0.1`	vulnerable
Ubuntu	libxml2	26.04	`2.15.2+dfsg-0.1ubuntu0.1`	vulnerable
Ubuntu	libxml2	26.04	`2.15.2+dfsg-0.1ubuntu0.2`	vulnerable
Ubuntu	libxml2	26.04	`2.15.2+dfsg-0.1ubuntu0.3`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libxml2	source	sid	`2.15.4+dfsg-1`	not yet assigned	Not reported	[1146744]
Debian	libxml2	source	forky	`2.15.4+dfsg-1`	not yet assigned	Not reported	[1146744]
Debian	libxml2	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1146744]
Debian	libxml2	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1146744]
Cpe	libxml2	cpe	Not reported	`2.15.4`	Not reported	NVD-CVE-2026-86143	Not reported
Ubuntu	libxml2	deb	noble	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	Not reported	Not reported
Ubuntu	libxml2-dev	deb	noble	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	Not reported	Not reported
Ubuntu	libxml2-doc	deb	noble	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	Not reported	Not reported
Ubuntu	libxml2-utils	deb	noble	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	Not reported	Not reported
Ubuntu	python3-libxml2	deb	noble	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	Not reported	Not reported
Ubuntu	libxml2	deb	pro	`2.9.10+dfsg-5ubuntu0.20.04.10+esm6`	Not reported	UBUNTU-CVE-2026-86143	Not reported
Ubuntu	libxml2	deb	22.04	`2.9.13+dfsg-1ubuntu0.14`	Not reported	UBUNTU-CVE-2026-86143	Not reported
Ubuntu	libxml2	deb	24.04	`2.9.14+dfsg-1.3ubuntu3.10`	Not reported	UBUNTU-CVE-2026-86143	Not reported
Ubuntu	libxml2	deb	26.04	`2.15.2+dfsg-0.1ubuntu0.3`	Not reported	UBUNTU-CVE-2026-86143	Not reported

[Debian bug #1146744]

Notes

[bookworm] libxml2: Minor issue

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libxml2]Affected
Details (4)
- 2.9.14+dfsg-1.3~deb12u6 · amd64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u6 · arm64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · amd64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · arm64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
[libxml2-dev]Affected
Source package: [libxml2]
Details (4)
- 2.9.14+dfsg-1.3~deb12u6 · amd64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u6 · arm64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · amd64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · arm64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
[libxml2-doc]Affected
Source package: [libxml2]
Details (4)
- 2.9.14+dfsg-1.3~deb12u6 · all · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u6 · all · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · all · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · all · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
[libxml2-utils]Affected
Source package: [libxml2]
Details (4)
- 2.9.14+dfsg-1.3~deb12u6 · amd64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u6 · arm64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · amd64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · arm64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
[python3-libxml2]Affected
Source package: [libxml2]
Details (4)
- 2.9.14+dfsg-1.3~deb12u6 · amd64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u6 · arm64 · bookworm
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · amd64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12
- 2.9.14+dfsg-1.3~deb12u4 · arm64 · bookworm-security
  Affected
  nvd · libxml2 · debian · bookworm; nvd · libxml2 · debian · 12

[Debian 13 (Trixie)]

[libxml2]Affected
Details (4)
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · amd64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · arm64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
[libxml2-dev]Affected
Source package: [libxml2]
Details (4)
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · amd64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · arm64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
[libxml2-doc]Affected
Source package: [libxml2]
Details (4)
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · all · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · all · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · all · trixie-security
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · all · trixie-security
  Affected
  nvd · libxml2 · debian · 13
[libxml2-utils]Affected
Source package: [libxml2]
Details (4)
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · amd64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · arm64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
[python3-libxml2]Affected
Source package: [libxml2]
Details (4)
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · amd64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u3 · arm64 · trixie
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13
- 2.12.7+dfsg+really2.9.14-2.1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · libxml2 · debian · 13

Observed: Oct 27, 2026, 6:50:15 AM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]