# CVE-2026-73639: libimager-perl: 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...

CVE-2026-73639 is fixed in libimager-perl on 1 platform by DEBIAN-CVE-2026-73639 (version 1.035+dfsg-1), released August 25, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-73639
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0070
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 17, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libimager-perl Debian 14 | 1.035+dfsg-1 | [DEBIAN-CVE-2026-73639](https://patchblox.com/security/data/fix/linux/debian-cve-2026-73639.md) | Aug 25, 2026 |

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