CVE-2026-56408: libexpat_project libexpat Integer Overflow or Wraparound
CVSS: 6.9v3.1MediumAnalyzed
AliasesALPINE-CVE-2026-56408UBUNTU-CVE-2026-56408DEBIAN-CVE-2026-56408CGA-23rg-cjhw-fmppCGA-27gc-gww7-xf4cCGA-77q3-jqp5-pm9qCGA-hpc5-6g7r-r4rpCGA-p8q2-2q8j-3g4fCGA-pf9w-48v9-4g6rCGA-qh6j-h9pj-wj7hCGA-qmmx-qw6x-38hw
Published 21-06-2026Last modified 22-06-2026
Vulnerability summary
CVE-2026-56408 is a medium (CVSS 6.9) Integer Overflow or Wraparound vulnerability in libexpat_project libexpat. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 1.9% of scored vulnerabilities.
CVSS score
6.9/10
010
Medium · v3.1 (CVE.org)EPSS score
0.13%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 10 · Related 10Timeline
- 21-06-2026PublishedVulnerability first disclosed.
- 22-06-2026Last modifiedVulnerability information updated.
Description
libexpat before 2.8.2 has an integer overflow in copyString.
CVSS metrics
7 scores · 7 sources · 1 versionMedium 6.9Preferred score · CVE.org (CNA)
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:LSourcesAll 7 agree
- OSV · AlpineEcosystem advisory · calculated6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
- OSV · UbuntuEcosystem advisory · calculated6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
- OSV · DebianEcosystem advisory · calculated6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
- OSV · WolfiEcosystem advisory · calculated6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
- OSV · ChainguardEcosystem advisory · calculated6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
- NVDNIST6.9MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
EPSS trend
Probability
0.13%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
0.00 pp
From 0.13% on 20-09-2026
20-09-202620-10-2026
EPSS score0.13%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu16 products
- ayttmAll versions (No fix recorded)
- cableswigAll versions (No fix recorded)
- cadaverAll versions (No fix recorded)
- coin3All versions (No fix recorded)
- expat< 2.2.5-3ubuntu0.9+esm4 | < 2.2.9-1ubuntu0.8+esm2 | < 2.4.7-1ubuntu0.8 | < 2.6.1-2ubuntu0.5 | All versions (No fix recorded) | < 2.7.4-1ubuntu0.1
Chainguard4 products
- expat< 2.8.2-r0
- expat-dev< 2.8.2-r0
- expat-doc< 2.8.2-r0
- libexpat1< 2.8.2-r0
Wolfi4 products
- expat< 2.8.2-r0
- expat-dev< 2.8.2-r0
- expat-doc< 2.8.2-r0
- libexpat1< 2.8.2-r0
Alpine1 product
- expat< 2.8.2-r0
Debian1 product
- expat< 2.5.0-1+deb12u3 | < 2.8.2-1~deb13u1 | < 2.8.2-1
Libexpat_project1 product
- libexpat< 2.8.2
6 vendors · 27 products
