CVE-2026-76956: libexpat_project libexpat Unexpected Status Code or Return Value
CVSS: 7.5v3.1HighAnalyzed
AliasesALPINE-CVE-2026-76956UBUNTU-CVE-2026-76956DEBIAN-CVE-2026-76956
Published 20-08-2026Last modified 20-08-2026
Vulnerability summary
CVE-2026-76956 is a high (CVSS 7.5) Unexpected Status Code or Return Value vulnerability in libexpat_project libexpat. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (NVD)EPSS score
0.29%
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 11 · Related 8Timeline
- 20-08-2026PublishedVulnerability first disclosed.
- 20-08-2026Last modifiedVulnerability information updated.
Description
In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code leads to insufficient entropy, which results in being vulnerable to hash flooding attacks, causing a denial of service via crafted XML content.
CVSS metrics
5 scores · 5 sources · 1 versionHigh 7.5Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSources5 sources · 5.9–7.5
- CVE.orgCNA5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HDiffers
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.29%
Chance of exploitation in the next 30 days
Percentile
20%
Versus all other CVEs
30-day change
0.00 pp
From 0.29% on 20-09-2026
20-09-202620-10-2026
EPSS score0.29%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu15 products
- ayttmAll versions (No fix recorded)
- cableswigAll versions (No fix recorded)
- cadaverAll versions (No fix recorded)
- coin3All versions (No fix recorded)
- gdcmAll versions (No fix recorded)
Alpine1 product
- expat< 2.8.4-r0
Debian1 product
- expatAll versions (No fix recorded) | < 2.9.0-1~deb13u1 | < 2.8.4-1
Libexpat_project1 product
- libexpat≥ 2.8.2, < 2.8.4
4 vendors · 18 products
