---
id: CVE-2026-73639
title: >-
  Imager::File::PNG versions from 1.003 before 1.004 for Perl write past the end
  of the row buffer reading a PNG with a tRNS transparency chunk in
  read_direct8.


  With a tRNS chunk, read_direct8() adds an alpha channel to the image it creat…
summary: >-
  Imager::File::PNG versions from 1.003 before 1.004 for Perl write past the end
  of the row buffer reading a PNG with a tRNS transparency chunk in
  read_direct8.


  With a tRNS chunk, read_direct8() adds an alpha channel to the image it creat…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-787
product: Imager-File-PNG
affected:
  - Imager-File-PNG >= 1.003 < 1.004
  - Imager >= 1.034 < 1.035
published: '2026-09-17'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:16:44.383'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73639'
references:
  - url: >-
      https://github.com/tonycoz/imager/commit/d973bd7e8843f084e8071caa24b89545c88b1e4b.patch
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://github.com/tonycoz/imager/pull/567'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://github.com/tonycoz/imager/security/advisories/GHSA-jhx5-34j8-9g88'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://metacpan.org/release/TONYC/Imager-1.035/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://metacpan.org/release/TONYC/Imager-File-PNG-1.004/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/17/6'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
epss: 0.00702
epssPercentile: 0.51231
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-22T18:04:27.077498Z'
ingestedAt: '2026-09-17T21:29:17.000Z'
---

## Overview

Imager::File::PNG versions from 1.003 before 1.004 for Perl write past the end of the row buffer reading a PNG with a tRNS transparency chunk in read_direct8.

With a tRNS chunk, read_direct8() adds an alpha channel to the image it creates but still sizes the row buffer from the original channel count. libpng expands the transparency into that extra channel, so png_read_row() fills one channel more than the buffer holds, at one byte per sample, and writes width bytes past the end of the allocation. Palette images go to read_paletted() and 16-bit images to read_direct16(), which sizes its buffer from png_get_rowbytes() and allocates enough for the expanded row.

The same reader ships bundled in the Imager distribution.

Reading an attacker-supplied PNG through Imager->read() corrupts the heap, which can crash the process.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.