---
cve: "CVE-2026-76641"
severity: "HIGH"
cvss: 8.7
epss: "0.4%"
vendor: "libexpat"
kev: false
exploited: false
published: "2026-08-20 18:16:51"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-22T21:51:46+02:00"
---

# CVE-2026-76641

> 8.7 HIGH · 🧪 PoC

## Beschreibung

Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 92810461043fce37e70079b37ab1f04490a8f039 (Commit)
- 98599f6dcc2b460410881fe420f5f55d6bec63bf (Commit)

## Referenzen

- <https://github.com/libexpat/libexpat/pull/1331>
- <https://github.com/libexpat/libexpat/commit/98599f6dcc2b460410881fe420f5f55d6bec63bf>
- <https://www.vulncheck.com/advisories/expat-out-of-bounds-read-via-dtdcopy>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-76641) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_