Red Hat Security Advisory: libXfont2 security update

Fixed packages 4

Vulnerabilities 2

• Critical 9.0
  CVE-2026-44950

  fs_read_glyphs() heap buffer overflow via cumulative glyph data overflow in libXfont2

  fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) copies each glyph's bitmap into a single buffer. Existing checks validates only that the source slice (position, length) lies within the source bitmap buffer. It does not check whether the…

  SUSE Image SLES15-SP6-SAP-Hardened-BYOS Image SLES15-SP7-SAP-GCE Image SLES-SAP-GCE-3P Debian Ubuntu Azure Linux
  Sep 10, 2026
• Critical 9.0
  CVE-2026-59679

  fs_read_glyphs() heap OOB read/write via encoding array index mismatch in libXfont2

  fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) indexes the per-character encoding[] array using num_chars from the FS_QueryXBitmaps16 reply, but that array was allocated with a size derived from num_extents in the separate FS_QueryXExt…

  SUSE Image SLES15-SP6-SAP-Azure-3P Image SLES15-SP6-SAPCAL-Azure Image SLES15-SP7-SAPCAL-Azure Debian Ubuntu Azure Linux
  Sep 10, 2026

References

• article
  https://access.redhat.com/security/updates/classification/#important
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2509620
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2509622
• advisory
  https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_55448.json
• report
  https://access.redhat.com/security/cve/CVE-2026-44950
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-44950
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-44950
• report
  https://access.redhat.com/security/cve/CVE-2026-59679
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-59679
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-59679