UBUNTU-CVE-2026-44950

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Source

https://ubuntu.com/security/CVE-2026-44950

Import Source

https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json

JSON Data

https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-44950

Upstream

CVE-2026-44950

Published

2026-09-10T09:17:00Z

Modified

2026-09-16T14:01:37Z

Severity

9.0 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H CVSS Calculator
9.5 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H CVSS Calculator
Ubuntu - medium

Summary

[none]

Details

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.

References

Affected packages

Ubuntu:16.04:LTS

libxfont2

Package

Name: libxfont2
Purl: pkg:deb/ubuntu/libxfont2?arch=source&distro=xenial

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.1-3~ubuntu16.04.1

1:2.0.1-3~ubuntu16.04.2

1:2.0.1-3~ubuntu16.04.3

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "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"

Ubuntu:22.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=jammy

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.4-1build3

1:2.0.5-1

1:2.0.5-1build1

1:2.0.5-1ubuntu0.2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "1:2.0.5-1ubuntu0.2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:24.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=noble

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.6-1

1:2.0.6-1build1

1:2.0.6-1+deb13u1build0.24.04.2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "1:2.0.6-1+deb13u1build0.24.04.2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:26.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=resolute

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.6-1build1

1:2.0.6-1build2

1:2.0.6-2

1:2.0.6-2ubuntu0.2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "1:2.0.6-2ubuntu0.2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:Pro:14.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=esm-infra-legacy%2Ftrusty

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:1.*

1:1.4.6-1

1:1.4.6-1ubuntu1

1:1.4.7-1

1:1.4.7-1ubuntu0.1

1:1.4.7-1ubuntu0.2

1:1.4.7-1ubuntu0.3

1:1.4.7-1ubuntu0.4

1:1.4.7-1ubuntu0.4+esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont1",
            "binary_version": "1:1.4.7-1ubuntu0.4+esm2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:Pro:16.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=esm-infra-legacy%2Fxenial

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:1.*

1:1.5.1-1

1:1.5.1-1ubuntu0.16.04.1

1:1.5.1-1ubuntu0.16.04.2

1:1.5.1-1ubuntu0.16.04.3

1:1.5.1-1ubuntu0.16.04.4

1:1.5.1-1ubuntu0.16.04.4+esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont1",
            "binary_version": "1:1.5.1-1ubuntu0.16.04.4+esm2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:Pro:18.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=esm-infra%2Fbionic

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.1-3ubuntu1

1:2.0.1-4

1:2.0.1-4ubuntu1

1:2.0.3-1

1:2.0.3-1ubuntu0.1~esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "1:2.0.3-1ubuntu0.1~esm2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"

Ubuntu:Pro:20.04:LTS

libxfont

Package

Name: libxfont
Purl: pkg:deb/ubuntu/libxfont?arch=source&distro=esm-infra%2Ffocal

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*

1:2.0.3-1

1:2.0.3-1ubuntu0.20.04.1~esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libxfont2",
            "binary_version": "1:2.0.3-1ubuntu0.20.04.1~esm2"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44950.json"