ubuntu-cve-2026-33636
Vulnerability from osv_ubuntu
Published
2026-03-26 17:16
Modified
2026-05-08 10:16
Summary
Details

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.

Severity
7.6 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libpng12-0",
            "binary_version": "1.2.50-1ubuntu2.14.04.3+esm1"
          },
          {
            "binary_name": "libpng3",
            "binary_version": "1.2.50-1ubuntu2.14.04.3+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "libpng",
        "purl": "pkg:deb/ubuntu/libpng@1.2.50-1ubuntu2.14.04.3+esm1?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.49-4ubuntu1",
        "1.2.49-5ubuntu1",
        "1.2.50-1ubuntu1",
        "1.2.50-1ubuntu2",
        "1.2.50-1ubuntu2.14.04.1",
        "1.2.50-1ubuntu2.14.04.2",
        "1.2.50-1ubuntu2.14.04.3",
        "1.2.50-1ubuntu2.14.04.3+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libpng12-0",
            "binary_version": "1.2.54-1ubuntu1.1+esm2"
          },
          {
            "binary_name": "libpng3",
            "binary_version": "1.2.54-1ubuntu1.1+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "libpng",
        "purl": "pkg:deb/ubuntu/libpng@1.2.54-1ubuntu1.1+esm2?arch=source\u0026distro=esm-infra/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.51-0ubuntu3",
        "1.2.54-1",
        "1.2.54-1ubuntu1",
        "1.2.54-1ubuntu1.1",
        "1.2.54-1ubuntu1.1+esm1",
        "1.2.54-1ubuntu1.1+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libpng-tools",
            "binary_version": "1.6.37-2ubuntu0.1~esm2"
          },
          {
            "binary_name": "libpng16-16",
            "binary_version": "1.6.37-2ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "libpng1.6",
        "purl": "pkg:deb/ubuntu/libpng1.6@1.6.37-2ubuntu0.1~esm2?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.37-1",
        "1.6.37-2",
        "1.6.37-2ubuntu0.1~esm1",
        "1.6.37-2ubuntu0.1~esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libpng-tools",
            "binary_version": "1.6.37-3ubuntu0.5"
          },
          {
            "binary_name": "libpng16-16",
            "binary_version": "1.6.37-3ubuntu0.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libpng1.6",
        "purl": "pkg:deb/ubuntu/libpng1.6@1.6.37-3ubuntu0.5?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.37-3ubuntu0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.37-3build4",
        "1.6.37-3build5",
        "1.6.37-3ubuntu0.1",
        "1.6.37-3ubuntu0.3",
        "1.6.37-3ubuntu0.4"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libpng-tools",
            "binary_version": "1.6.43-5ubuntu0.6"
          },
          {
            "binary_name": "libpng16-16t64",
            "binary_version": "1.6.43-5ubuntu0.6"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libpng1.6",
        "purl": "pkg:deb/ubuntu/libpng1.6@1.6.43-5ubuntu0.6?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.43-5ubuntu0.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.40-1",
        "1.6.40-2",
        "1.6.40-3",
        "1.6.42-1",
        "1.6.43-1",
        "1.6.43-3",
        "1.6.43-5build1",
        "1.6.43-5ubuntu0.1",
        "1.6.43-5ubuntu0.3",
        "1.6.43-5ubuntu0.4",
        "1.6.43-5ubuntu0.5"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libpng-tools",
            "binary_version": "1.6.50-1ubuntu0.5"
          },
          {
            "binary_name": "libpng16-16t64",
            "binary_version": "1.6.50-1ubuntu0.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "libpng1.6",
        "purl": "pkg:deb/ubuntu/libpng1.6@1.6.50-1ubuntu0.5?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.50-1ubuntu0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.47-1.1",
        "1.6.48-1",
        "1.6.49-1~exp1",
        "1.6.50-1~exp1",
        "1.6.50-1",
        "1.6.50-1ubuntu0.1",
        "1.6.50-1ubuntu0.3",
        "1.6.50-1ubuntu0.4"
      ]
    }
  ],
  "aliases": [],
  "details": "LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng\u0027s ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.",
  "id": "UBUNTU-CVE-2026-33636",
  "modified": "2026-05-08T10:16:56Z",
  "published": "2026-03-26T17:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-33636"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-33636"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/pnggroup/libpng/security/advisories/GHSA-wjr5-c57x-95m2"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8251-1"
    }
  ],
  "related": [
    "USN-8251-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-33636"
  ]
}



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