CVE catalog

CVE-2026-56403

libexpat before 2.8.2 has an integer overflow in storeAtts.

Severity: Medium · CVSS 6.9CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
Published: May 10, 2026, 7:16:07 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.17% · Oct 22, 2026

libexpat before 2.8.2 has an integer overflow in storeAtts.

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	expat	sid	`2.9.0-1`	fixed
Debian	expat	forky	`2.9.0-1`	fixed
Debian	expat	trixie	`2.8.3-1~deb13u1`	fixed
Debian	expat	trixie-security	`2.9.0-1~deb13u1`	fixed
Debian	expat	bookworm	`2.5.0-1+deb12u2`	vulnerable
Debian	expat	bookworm-security	`2.5.0-1+deb12u5`	fixed
Cpe	expat	Not reported	Not reported	vulnerable
Cpe	libexpat	Not reported	`2.8.2`	fixed
Ubuntu	expat	noble	`2.6.1-2ubuntu0.5`	fixed
Ubuntu	libexpat1	noble	`2.6.1-2ubuntu0.5`	fixed
Ubuntu	libexpat1-dev	noble	`2.6.1-2ubuntu0.5`	fixed
Alpine	expat	3.21	`2.8.2-r0`	fixed
Alpine	expat	3.22	`2.8.2-r0`	fixed
Alpine	expat	3.23	`2.8.2-r0`	fixed
Alpine	expat	3.24	`2.8.2-r0`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	expat	source	sid	`2.8.2-1`	not yet assigned	Not reported	[1140557]
Debian	expat	source	forky	`2.8.2-1`	not yet assigned	Not reported	[1140557]
Debian	expat	source	trixie	`2.8.2-1~deb13u1`	not yet assigned	Not reported	[1140557]
Debian	expat	source	bookworm	`2.5.0-1+deb12u3`	not yet assigned	Not reported	[1140557]
Cpe	libexpat	cpe	Not reported	`2.8.2`	Not reported	Not reported	Not reported
Ubuntu	expat	deb	noble	`2.6.1-2ubuntu0.5`	Not reported	Not reported	Not reported
Ubuntu	libexpat1	deb	noble	`2.6.1-2ubuntu0.5`	Not reported	Not reported	Not reported
Ubuntu	libexpat1-dev	deb	noble	`2.6.1-2ubuntu0.5`	Not reported	Not reported	Not reported
Alpine	expat	apk	3.21	`2.8.2-r0`	Not reported	ALPINE-CVE-2026-56403	Not reported
Alpine	expat	apk	3.22	`2.8.2-r0`	Not reported	ALPINE-CVE-2026-56403	Not reported
Alpine	expat	apk	3.23	`2.8.2-r0`	Not reported	ALPINE-CVE-2026-56403	Not reported
Alpine	expat	apk	3.24	`2.8.2-r0`	Not reported	ALPINE-CVE-2026-56403	Not reported

[Debian bug #1140557]

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[expat]Unknown
Details (4)
- 2.5.0-1+deb12u2 · amd64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u2 · arm64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · amd64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · arm64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
[libexpat1]Unknown
Source package: [expat]
Details (4)
- 2.5.0-1+deb12u2 · amd64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u2 · arm64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · amd64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · arm64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
[libexpat1-dev]Unknown
Source package: [expat]
Details (4)
- 2.5.0-1+deb12u2 · amd64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u2 · arm64 · bookworm
  Affected · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · amd64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12
- 2.5.0-1+deb12u3 · arm64 · bookworm-security
  Fixed · Fixed: 2.5.0-1+deb12u3
  nvd · expat · debian · bookworm; nvd · expat · debian · 12

[Debian 13 (Trixie)]

[expat]Unknown
Details (6)
- 2.7.1-2 · amd64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.7.1-2 · arm64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.2-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.9.0-1~deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
[libexpat1]Unknown
Source package: [expat]
Details (6)
- 2.7.1-2 · amd64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.7.1-2 · arm64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.2-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.9.0-1~deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
[libexpat1-dev]Unknown
Source package: [expat]
Details (6)
- 2.7.1-2 · amd64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.7.1-2 · arm64 · trixie
  Affected · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.2-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.8.3-1~deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13
- 2.9.0-1~deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 2.8.2-1~deb13u1
  nvd · expat · debian · 13

Observed: Oct 23, 2026, 10:03:59 PM UTC

References

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