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Medium RLSA-2021:2569 5 CVEs

Moderate: libxml2 security update

Published Jun 29, 2021 · Updated Feb 4, 2026

Ecosystem: Rocky Linux

Summary

The libxml2 library is a development toolbox providing the implementation of various XML standards.

Security Fix(es):

* libxml2: Use-after-free in xmlEncodeEntitiesInternal() in entities.c (CVE-2021-3516)

* libxml2: Heap-based buffer overflow in xmlEncodeEntitiesInternal() in entities.c (CVE-2021-3517)

* libxml2: Use-after-free in xmlXIncludeDoProcess() in xinclude.c (CVE-2021-3518)

* libxml2: NULL pointer dereference when post-validating mixed content parsed in recovery mode (CVE-2021-3537)

* libxml2: Exponential entity expansion attack bypasses all existing protection mechanisms (CVE-2021-3541)

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 1

ReleasePackageFixed in
Rocky Linux · 8 libxml2 0:2.9.7-9.el8_4.2

Vulnerabilities 5

  • High 8.8
    CVE-2021-3518 EPSS 22%

    Nokogiri Implements libxml2 version vulnerable to use-after-free

    There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, an…

    libxml2 libxml2 nokogiri libxml2 Debian Ubuntu Alpine RubyGems
  • High 8.6
    CVE-2021-3517 EPSS 17%

    Nokogiri contains libxml Out-of-bounds Write vulnerability

    There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds …

    qt5-qtwebengine libxml2 libxml2 nokogiri Debian Ubuntu Alpine RubyGems
  • Medium 5.9
    CVE-2021-3537

    Nokogiri Implements libxml2 version vulnerable to null pointer dereferencing

    A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used …

    libxml2 libxml2 nokogiri libxml2 Debian Ubuntu Alpine RubyGems
  • Unscored —
    CVE-2021-3516

    There's a flaw in libxml2's xmllint in versions before 2.9.11. An attacker who is able to submit a crafted file to be p…

    libxml2 libxml2 Debian Ubuntu
  • Unscored —
    CVE-2021-3541

    A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechani…

    qt5-qtwebengine libxml2 libxml2 libxml2 Debian Ubuntu Alpine

References

  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=1950515
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=1954225
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=1954232
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=1954242
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=1956522