Summary
Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2026-59679: A flaw was found in the libXfont2 font-server client. A remote attacker, by operating a malicious font server, could exploit an out-of-bounds read/write vulnerability. This occurs because the client incorrectly handles font data, leading to an out-of-bounds memory access. This can lead to privilege escalation if the X server runs with root privileges, or a denial of service (crash) if it runs as an unprivileged user. CVE-2026-44950: A flaw was found in the libXfont2 font-server client. This heap buffer overflow vulnerability allows a malicious font server to send specially crafted glyph data. The fs_read_glyphs() function fails to properly validate the total size of the incoming data, leading to an overwrite of memory beyond the intended buffer. If the X server runs as a privileged user, this could result in privilege escalation, allowing an attacker to gain higher access. If the X server runs as an unprivileged user, it could lead to a denial of service, causing the system to crash.
Fixed packages 3
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2 | libXfont2 | 0:2.0.3-1.amzn2.0.2 |
| Amazon Linux · 2 | libXfont2-debuginfo | 0:2.0.3-1.amzn2.0.2 |
| Amazon Linux · 2 | libXfont2-devel | 0:2.0.3-1.amzn2.0.2 |
Vulnerabilities 2
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Critical 9.0
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…
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Critical 9.0
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…