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DEBIAN-CVE-2026-33416

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 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.

Announced Group revision 1
Original source ↗

DEBIAN-CVE-2026-33416

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-2026-33416

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-2026-33416.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-2026-33416.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-2026-33416.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#56362 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. DEBIAN-CVE-2026-33416 · Revision 1Source updated