Vulnerability Details CVE-2026-118370
libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 38.4%
CVSS Severity
CVSS v3 Score 5.9
References
- https://github.com/libexpat/libexpat
- https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L4138-L4140
- https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae
- https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c
- https://github.com/libexpat/libexpat/pull/1450
- https://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes
Products affected by CVE-2026-118370
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cpe:2.3:a:libexpat_project:libexpat:-
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cpe:2.3:a:libexpat_project:libexpat:1.95.0
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cpe:2.3:a:libexpat_project:libexpat:1.95.1
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cpe:2.3:a:libexpat_project:libexpat:1.95.2
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cpe:2.3:a:libexpat_project:libexpat:1.95.3
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cpe:2.3:a:libexpat_project:libexpat:1.95.4
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cpe:2.3:a:libexpat_project:libexpat:1.95.5
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cpe:2.3:a:libexpat_project:libexpat:1.95.6
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cpe:2.3:a:libexpat_project:libexpat:1.95.7
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cpe:2.3:a:libexpat_project:libexpat:1.95.8
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cpe:2.3:a:libexpat_project:libexpat:2.0.0
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cpe:2.3:a:libexpat_project:libexpat:2.0.1
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cpe:2.3:a:libexpat_project:libexpat:2.1.0
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cpe:2.3:a:libexpat_project:libexpat:2.1.1
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cpe:2.3:a:libexpat_project:libexpat:2.2.0
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cpe:2.3:a:libexpat_project:libexpat:2.2.1
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cpe:2.3:a:libexpat_project:libexpat:2.2.10
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cpe:2.3:a:libexpat_project:libexpat:2.2.2
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cpe:2.3:a:libexpat_project:libexpat:2.2.3
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cpe:2.3:a:libexpat_project:libexpat:2.2.4
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cpe:2.3:a:libexpat_project:libexpat:2.2.5
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cpe:2.3:a:libexpat_project:libexpat:2.2.6
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cpe:2.3:a:libexpat_project:libexpat:2.2.7
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cpe:2.3:a:libexpat_project:libexpat:2.2.8
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cpe:2.3:a:libexpat_project:libexpat:2.2.9
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cpe:2.3:a:libexpat_project:libexpat:2.3.0
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cpe:2.3:a:libexpat_project:libexpat:2.4.0
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cpe:2.3:a:libexpat_project:libexpat:2.4.1
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cpe:2.3:a:libexpat_project:libexpat:2.4.3
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cpe:2.3:a:libexpat_project:libexpat:2.4.4
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cpe:2.3:a:libexpat_project:libexpat:2.4.5
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cpe:2.3:a:libexpat_project:libexpat:2.4.6
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cpe:2.3:a:libexpat_project:libexpat:2.4.7
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cpe:2.3:a:libexpat_project:libexpat:2.4.8
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cpe:2.3:a:libexpat_project:libexpat:2.4.9
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cpe:2.3:a:libexpat_project:libexpat:2.5.0
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cpe:2.3:a:libexpat_project:libexpat:2.6.0
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cpe:2.3:a:libexpat_project:libexpat:2.6.1
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cpe:2.3:a:libexpat_project:libexpat:2.6.2
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cpe:2.3:a:libexpat_project:libexpat:2.6.3
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cpe:2.3:a:libexpat_project:libexpat:2.6.4
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cpe:2.3:a:libexpat_project:libexpat:2.7.0
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cpe:2.3:a:libexpat_project:libexpat:2.7.1
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cpe:2.3:a:libexpat_project:libexpat:2.7.2
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cpe:2.3:a:libexpat_project:libexpat:2.7.3
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cpe:2.3:a:libexpat_project:libexpat:2.7.4
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cpe:2.3:a:libexpat_project:libexpat:2.7.5
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cpe:2.3:a:libexpat_project:libexpat:2.8.0
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cpe:2.3:a:libexpat_project:libexpat:2.8.1
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cpe:2.3:a:libexpat_project:libexpat:2.8.2
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cpe:2.3:a:libexpat_project:libexpat:2.8.3
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cpe:2.3:a:libexpat_project:libexpat:2.8.4