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libexpat

9 known vulnerabilities.

libexpat at a glance

Last 12 months
9
Critical · all time
0
Exploited · all time
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Public exploit · all time
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New vulnerabilities per month · last 12 months
0 3 5 December 2025: 0 vulnerabilities Dec 2025 January 2026: 0 vulnerabilities February 2026: 0 vulnerabilities March 2026: 0 vulnerabilities Mar April 2026: 0 vulnerabilities May 2026: 0 vulnerabilities June 2026: 0 vulnerabilities Jun July 2026: 0 vulnerabilities August 2026: 1 vulnerability September 2026: 2 vulnerabilities Sep October 2026: 5 vulnerabilities November 2026: 1 vulnerability
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9 results · Feed

  • Medium 4.8

    libexpat through 2.10.0 Out-of-Bounds Read via unknown_toUtf8 and unknown_toUtf16

    libexpat through 2.10.0 contains an out-of-bounds read vulnerability in unknown_toUtf8() and unknown_toUtf16() in xmltok.c when handling application-registered unknown encodings. Attackers can supply a document ending in a truncated multibyte sequence so the …

  • Medium 5.9

    libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes

    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 carr…

  • Medium 5.9

    libexpat through 2.9.0 NULL Pointer Dereference via External Entity Subparser

    libexpat through 2.9.0 contains a NULL pointer dereference vulnerability in externalEntityInitProcessor2() in lib/xmlparse.c that mishandles the XML_TOK_NONE token from empty input. Attackers who control stream chunking can force an empty non-final first pars…

  • High 7.5

    libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

    libexpat through 2.9.0 contains a denial of service vulnerability because billion laughs protection in accountingDiffTolerated() in xmlparse.c detects entity amplification too late. Attackers can supply a moderately sized XML document with a large DTD and nes…

  • Medium 5.9

    libexpat 2.7.2 through 2.9.0 Denial of Service via XML_ParserReset

    libexpat 2.7.2 through 2.9.0 contains a denial of service vulnerability because XML_ParserReset zeroes the direct byte count but never offsets tracked heap allocations. Attackers can submit a large XML document so later documents on the same reset parser fail…

  • High 8.2

    libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer

    libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, …

  • Medium 5.9

    libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc

    libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap …

  • High 7.5

    Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate

    Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following c…

  • High 7.5

    Expat Out-of-Bounds Read via dtdCopy

    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 …