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DEBIAN-CVE-2026-33636

Type: advisorySource: OSV1 source record

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.

Announced Group revision 1
Original source ↗

DEBIAN-CVE-2026-33636

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-2026-33636

libpng1.6

Source reference: /affected/0/package/name

Affected versions
1.6.39-2

Source reference: /affected/0/versions

1.6.39-2+deb12u1

Source reference: /affected/0/versions

1.6.39-2+deb12u2

Source reference: /affected/0/versions

1.6.39-2+deb12u3

Source reference: /affected/0/versions

Fixed versions
1.6.39-2+deb12u4

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

libpng1.6

Source reference: /affected/1/package/name

Affected versions
1.6.48-1

Source reference: /affected/1/versions

1.6.48-1+deb13u1

Source reference: /affected/1/versions

1.6.48-1+deb13u2

Source reference: /affected/1/versions

1.6.48-1+deb13u3

Source reference: /affected/1/versions

Fixed versions
1.6.48-1+deb13u4

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

libpng1.6

Source reference: /affected/2/package/name

Affected versions
1.6.48-1

Source reference: /affected/2/versions

1.6.49-1~exp1

Source reference: /affected/2/versions

1.6.50-1

Source reference: /affected/2/versions

1.6.50-1~exp1

Source reference: /affected/2/versions

1.6.51-1

Source reference: /affected/2/versions

1.6.52-1

Source reference: /affected/2/versions

1.6.53-1

Source reference: /affected/2/versions

1.6.54-1

Source reference: /affected/2/versions

1.6.55-1

Source reference: /affected/2/versions

Fixed versions
1.6.56-1

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"
          },
          {
            "fixed": "1.6.39-2+deb12u4"
          }
        ]
      }
    ],
    "package": {
      "name": "libpng1.6",
      "purl": "pkg:deb/debian/libpng1.6?arch=source&distro=bookworm",
      "ecosystem": "Debian:12"
    },
    "versions": [
      "1.6.39-2",
      "1.6.39-2+deb12u1",
      "1.6.39-2+deb12u2",
      "1.6.39-2+deb12u3"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33636.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1.6.48-1+deb13u4"
          }
        ]
      }
    ],
    "package": {
      "name": "libpng1.6",
      "purl": "pkg:deb/debian/libpng1.6?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "1.6.48-1",
      "1.6.48-1+deb13u1",
      "1.6.48-1+deb13u2",
      "1.6.48-1+deb13u3"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33636.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1.6.56-1"
          }
        ]
      }
    ],
    "package": {
      "name": "libpng1.6",
      "purl": "pkg:deb/debian/libpng1.6?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "1.6.48-1",
      "1.6.49-1~exp1",
      "1.6.50-1",
      "1.6.50-1~exp1",
      "1.6.51-1",
      "1.6.52-1",
      "1.6.53-1",
      "1.6.54-1",
      "1.6.55-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33636.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#56791 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. DEBIAN-CVE-2026-33636 · Revision 1Source updated