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OpenAdvisories
High RLSA-2026:98478 4 CVEs

Important: expat security update

Published Nov 13, 2026 · Updated Nov 13, 2026

Ecosystem: Rocky Linux

Summary

Expat is a C library for parsing XML documents.

Security Fix(es):

* expat: Expat: Denial of Service via quadratic complexity in attribute processing (CVE-2026-66046)

* expat: Expat: XML Injection via Malformed UTF-16 Input (CVE-2026-93990)

* expat: expat: Denial of Service via integer overflow in expat_realloc (CVE-2026-102633)

* expat: expat: Information disclosure via heap buffer over-read in XML_ParseBuffer (CVE-2026-77214)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Fixed packages 20

ReleasePackageFixed in
Rocky Linux · 9 expat 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debuginfo 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debuginfo 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debuginfo 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debuginfo 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debuginfo 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debugsource 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debugsource 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debugsource 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debugsource 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-debugsource 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-devel 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-devel 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-devel 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-devel 0:2.5.0-9.el9_9.4
Rocky Linux · 9 expat-devel 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

  • 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://access.redhat.com/errata/RHSA-2026:98478