UBUNTU-CVE-2026-33018

See a problem?
Please try reporting it to the source first.
Source
https://ubuntu.com/security/CVE-2026-33018
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json
JSON Data
https://api.test.osv.dev/v1/vulns/UBUNTU-CVE-2026-33018
Upstream
  • CVE-2026-33018
Published
2026-04-14T22:16:00Z
Modified
2026-04-16T11:05:23.299870Z
Severity
  • 7.0 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the loadgif() function in fromgif.c, where a single sixelframet object is reused across all frames of an animated GIF and gifinitframe() unconditionally frees and reallocates frame->pixels between frames without consulting the object's reference count. Because the public API explicitly provides sixelframeref() to retain a frame and sixelframegetpixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixelhelperloadimagefile() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.

References

Affected packages

Ubuntu:16.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.5.2-2?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.4.2-1
1.5.2-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.5.2-2",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.5.2-2",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.5.2-2",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"
Ubuntu:18.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.7.3-1?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.5.2-2
1.7.3-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.7.3-1",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.7.3-1",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.7.3-1",
            "binary_name": "libsixel-examples"
        },
        {
            "binary_version": "1.7.3-1",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"
Ubuntu:20.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.8.2-2.1?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.8.2-1
1.8.2-2.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.8.2-2.1",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.8.2-2.1",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.8.2-2.1",
            "binary_name": "libsixel-examples"
        },
        {
            "binary_version": "1.8.2-2.1",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"
Ubuntu:22.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.10.3-3?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.8.6-2
1.10.3-2
1.10.3-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.10.3-3",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.10.3-3",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.10.3-3",
            "binary_name": "libsixel-examples"
        },
        {
            "binary_version": "1.10.3-3",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"
Ubuntu:24.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.10.3-3build1?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.10.3-3
1.10.3-3build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.10.3-3build1",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.10.3-3build1",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.10.3-3build1",
            "binary_name": "libsixel-examples"
        },
        {
            "binary_version": "1.10.3-3build1",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"
Ubuntu:25.10
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel@1.10.5-1?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.10.5-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.10.5-1",
            "binary_name": "libsixel-bin"
        },
        {
            "binary_version": "1.10.5-1",
            "binary_name": "libsixel-dev"
        },
        {
            "binary_version": "1.10.5-1",
            "binary_name": "libsixel-examples"
        },
        {
            "binary_version": "1.10.5-1",
            "binary_name": "libsixel1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33018.json"