Libexpat Project: >> Libexpat >> 2.2.10 Security Vulnerabilities
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
CVSS Score
4.9
EPSS Score
0.001
Published
2026-08-20
Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.
CVSS Score
8.7
EPSS Score
0.006
Published
2026-08-18
xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations.
CVSS Score
6.9
EPSS Score
0.002
Published
2026-06-21
libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.
CVSS Score
4.9
EPSS Score
0.002
Published
2026-06-21
libexpat before 2.8.2 has an integer overflow in copyString.
CVSS Score
6.9
EPSS Score
0.001
Published
2026-06-21
xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.
CVSS Score
6.5
EPSS Score
0.001
Published
2026-06-21
xmlwf in libexpat before 2.8.2 has an integer overflow in resolveSystemId.
CVSS Score
6.9
EPSS Score
0.002
Published
2026-06-21
libexpat before 2.8.2 has an integer overflow in addBinding.
CVSS Score
6.9
EPSS Score
0.002
Published
2026-06-21
libexpat before 2.8.2 has an integer overflow in getAttributeId.
CVSS Score
6.9
EPSS Score
0.001
Published
2026-06-21
libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse.
CVSS Score
6.9
EPSS Score
0.001
Published
2026-06-21
Page 1