UBUNTU-CVE-2026-44636

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Source
https://ubuntu.com/security/CVE-2026-44636
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-44636
Upstream
Published
2026-05-14T20:17:00Z
Modified
2026-05-20T22:03:08Z
Severity
  • 7.4 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/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. From to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buffer overflow. The public sixel_encode entry point validates only that width and height are greater than zero, with no upper bound. width and height are multiplied as plain int when computing the allocation size for paletted_pixels and normalized_pixels. Any caller that asks libsixel to encode a pixel buffer with width times height greater than INT_MAX (about 2.15 billion) will hit a wrapped allocation size; under the right wrap, the malloc succeeds with a buffer much smaller than the encoder expects, and the encoder writes past the end of the heap allocation. This vulnerability is fixed in 1.8.7-r2.

References

Affected packages

Ubuntu:16.04:LTS
libsixel

Package

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

Affected ranges

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

Affected versions

1.*
1.4.2-1
1.5.2-2

Ecosystem specific 

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

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:18.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel?arch=source&distro=bionic

Affected ranges

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

Affected versions

1.*
1.5.2-2
1.7.3-1

Ecosystem specific 

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

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:20.04:LTS
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel?arch=source&distro=focal

Affected ranges

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

Affected versions

1.*
1.8.2-1
1.8.2-2.1

Ecosystem specific 

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

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:22.04:LTS
libsixel

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown 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_name": "libsixel-bin",
            "binary_version": "1.10.3-3"
        },
        {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.3-3"
        },
        {
            "binary_name": "libsixel1",
            "binary_version": "1.10.3-3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:24.04:LTS
libsixel

Package

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

Affected ranges

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

Affected versions

1.*
1.10.3-3
1.10.3-3build1

Ecosystem specific 

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

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:25.10
libsixel

Package

Name
libsixel
Purl
pkg:deb/ubuntu/libsixel?arch=source&distro=questing

Affected ranges

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

Affected versions

1.*
1.10.5-1

Ecosystem specific 

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

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"
Ubuntu:26.04:LTS
libsixel

Package

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

Affected ranges

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

Affected versions

1.*
1.10.5-1
1.10.5-1build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libsixel-bin",
            "binary_version": "1.10.5-1build1"
        },
        {
            "binary_name": "libsixel-examples",
            "binary_version": "1.10.5-1build1"
        },
        {
            "binary_name": "libsixel1",
            "binary_version": "1.10.5-1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44636.json"