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DEBIAN-CVE-2026-44950

Type: advisorySource: OSV1 source record

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.

Announced Source revision 1
Original source ↗

DEBIAN-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:DEBIAN-CVE-2026-44950

libxfont

Source reference: /affected/0/package/name

Affected versions
1:2.0.6-1

Source reference: /affected/0/versions

1:2.0.6-1+deb12u1

Source reference: /affected/0/versions

1:2.0.6-1+hurd.1

Source reference: /affected/0/versions

1:2.0.6-2

Source reference: /affected/0/versions

1:2.0.8-1

Source reference: /affected/0/versions

1:2.0.9-1

Source reference: /affected/0/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

libxfont

Source reference: /affected/1/package/name

Affected versions
1:2.0.6-1

Source reference: /affected/1/versions

1:2.0.6-1+deb13u1

Source reference: /affected/1/versions

1:2.0.6-1+hurd.1

Source reference: /affected/1/versions

1:2.0.6-2

Source reference: /affected/1/versions

1:2.0.8-1

Source reference: /affected/1/versions

1:2.0.9-1

Source reference: /affected/1/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

libxfont

Source reference: /affected/2/package/name

Affected versions
1:2.0.6-1

Source reference: /affected/2/versions

1:2.0.6-1+hurd.1

Source reference: /affected/2/versions

1:2.0.6-2

Source reference: /affected/2/versions

1:2.0.8-1

Source reference: /affected/2/versions

Fixed versions
1:2.0.9-1

Source reference: /affected/2/ranges

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": "libxfont",
      "purl": "pkg:deb/debian/libxfont?arch=source&distro=bookworm",
      "ecosystem": "Debian:12"
    },
    "versions": [
      "1:2.0.6-1",
      "1:2.0.6-1+deb12u1",
      "1:2.0.6-1+hurd.1",
      "1:2.0.6-2",
      "1:2.0.8-1",
      "1:2.0.9-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44950.json"
    },
    "ecosystem_specific": {
      "urgency": "unimportant"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          }
        ]
      }
    ],
    "package": {
      "name": "libxfont",
      "purl": "pkg:deb/debian/libxfont?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "1:2.0.6-1",
      "1:2.0.6-1+deb13u1",
      "1:2.0.6-1+hurd.1",
      "1:2.0.6-2",
      "1:2.0.8-1",
      "1:2.0.9-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44950.json"
    },
    "ecosystem_specific": {
      "urgency": "unimportant"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1:2.0.9-1"
          }
        ]
      }
    ],
    "package": {
      "name": "libxfont",
      "purl": "pkg:deb/debian/libxfont?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "1:2.0.6-1",
      "1:2.0.6-1+hurd.1",
      "1:2.0.6-2",
      "1:2.0.8-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-44950.json"
    },
    "ecosystem_specific": {
      "urgency": "unimportant"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#56539 · Revision 1
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Publisher date
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