libexpat Expat up to 2.8.3 External Entity Parser XML_ExternalEntityParserCreate out-of-bounds

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.3$0-$5k0.95

Summaryinfo

A vulnerability classified as problematic was found in libexpat Expat up to 2.8.3. The affected element is the function XML_ExternalEntityParserCreate of the component External Entity Parser. Such manipulation leads to out-of-bounds. This vulnerability is documented as CVE-2026-76641. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in libexpat Expat up to 2.8.3. Affected by this issue is the function XML_ExternalEntityParserCreate of the component External Entity Parser. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-76641 since 08/19/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/20/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

08/19/2026 CVE reserved
08/20/2026 +1 days Advisory disclosed
08/20/2026 +0 days VulDB entry created
08/20/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Not defined

CVE: CVE-2026-76641 (🔒)
GCVE (CVE): GCVE-0-2026-76641
GCVE (VulDB): GCVE-100-393806

Entryinfo

Created: 08/20/2026 19:55
Changes: 08/20/2026 19:55 (75)
Complete: 🔍
Cache ID: 216::103

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