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OpenAdvisories
High RHSA-2026:72663 2 CVEs

Red Hat Security Advisory: expat security update

Published Sep 30, 2026 · Updated Oct 15, 2026

Ecosystem: Red Hat

Fixed packages 6

ReleasePackageFixed in
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-debuginfo 0:2.5.0-6.el9_8.5
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-debugsource 0:2.5.0-6.el9_8.5
Red Hat · RHEL 9 enterprise_linux:9::appstream expat-devel 0:2.5.0-6.el9_8.5
Red Hat · RHEL 9 enterprise_linux:9::baseos expat 0:2.5.0-6.el9_8.5
Red Hat · RHEL 9 enterprise_linux:9::baseos expat-debuginfo 0:2.5.0-6.el9_8.5
Red Hat · RHEL 9 enterprise_linux:9::baseos expat-debugsource 0:2.5.0-6.el9_8.5

Vulnerabilities 2

  • 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

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
  • advisory
    https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_72663.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-2026-93990
  • 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