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OpenAdvisories
High RHSA-2026:98478 4 CVEs

Red Hat Security Advisory: expat security update

Published Nov 13, 2026 · Updated Nov 13, 2026

Ecosystem: Red Hat

Fixed packages 6

ReleasePackageFixed in
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-debuginfo 0:2.5.0-9.el9_9.4
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-debugsource 0:2.5.0-9.el9_9.4
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-devel 0:2.5.0-9.el9_9.4
Red Hat · RHEL 9 enterprise_linux:9::baseos expat 0:2.5.0-9.el9_9.4
Red Hat · RHEL 9 enterprise_linux:9::baseos expat-debuginfo 0:2.5.0-9.el9_9.4
Red Hat · RHEL 9 enterprise_linux:9::baseos expat-debugsource 0:2.5.0-9.el9_9.4

Vulnerabilities 4

  • High 8.2
    CVE-2026-77214

    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, …

    libexpat project libexpat insighttoolkit4 cmake Debian Ubuntu Azure Linux Alpine
  • High 7.5
    CVE-2026-66046

    Expat Denial of Service via storeAtts() Quadratic Complexity

    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 elementTy…

    libexpat project libexpat insighttoolkit4 expat Debian Ubuntu Azure Linux Alpine
  • High 7.5
    CVE-2026-93990

    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…

    libexpat project libexpat python3 insighttoolkit4 Debian Ubuntu Azure Linux Alpine
  • Medium 5.9
    CVE-2026-102633

    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 …

    libexpat project libexpat insighttoolkit4 expat Debian Ubuntu Azure Linux Alpine

References

  • article
    https://access.redhat.com/security/updates/classification/#important
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517901
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2538967
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543288
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2547476
  • advisory
    https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_98478.json
  • report
    https://access.redhat.com/security/cve/CVE-2026-66046
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-66046
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-66046
  • article
    https://github.com/libexpat/libexpat/pull/1321
  • article
    https://www.vulncheck.com/advisories/expat-denial-of-service-via-storeatts-quadratic-complexity
  • report
    https://access.redhat.com/security/cve/CVE-2026-77214
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-77214
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-77214
  • article
    https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0
  • article
    https://github.com/libexpat/libexpat/pull/1393
  • article
    https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer
  • report
    https://access.redhat.com/security/cve/CVE-2026-93990
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-93990
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-93990
  • article
    https://github.com/libexpat/libexpat
  • article
    https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a
  • article
    https://github.com/libexpat/libexpat/pull/1282
  • article
    https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate
  • report
    https://access.redhat.com/security/cve/CVE-2026-102633
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-102633
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-102633
  • article
    https://github.com/libexpat/libexpat/blob/R_2_8_5/expat/lib/xmlparse.c#L1003
  • article
    https://github.com/libexpat/libexpat/commit/209801d7fbaf07ab74bae8cb32dd2ab9e5846118
  • article
    https://github.com/libexpat/libexpat/pull/1392
  • article
    https://www.vulncheck.com/advisories/libexpat-2.7.2-through-2.8.5-integer-overflow-in-expat-realloc