UBUNTU-CVE-2026-44950
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 running destination cursor has exceeded the allocation. A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the existing validation, but the cumulative writes total 64000 bytes into a 64-byte destination buffer. This is a heap buffer overflow with attacker-controlled content.
UBUNTU-CVE-2026-44950
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:UBUNTU-CVE-2026-44950
libxfont2
Source reference: /affected/0/package/name
- Affected versions
- 1:2.0.1-3~ubuntu16.04.1
Source reference:
/affected/0/versions1:2.0.1-3~ubuntu16.04.2Source reference:
/affected/0/versions1:2.0.1-3~ubuntu16.04.3Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libxfont2",
"purl": "pkg:deb/ubuntu/libxfont2?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1:2.0.1-3~ubuntu16.04.1",
"1:2.0.1-3~ubuntu16.04.2",
"1:2.0.1-3~ubuntu16.04.3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libxfont2",
"binary_version": "1:2.0.1-3~ubuntu16.04.3"
}
]
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #23442 · Revision 1
- Added to Heist Feed
- Publisher date