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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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Vendor Solution
Upgrade to Imager-File-PNG 1.004 or later, or to Imager 1.035 or later if the bundled copy is in use.
Tracking
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Thu, 17 Sep 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| 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 | |
| Weaknesses | CWE-787 | |
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Subscriptions
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-09-17T21:18:59.207Z
Reserved: 2026-08-13T12:51:42.912Z
Link: CVE-2026-73639
Vulnrichment
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NVD
Status : Received
Published: 2026-09-17T22:17:03.763
Modified: 2026-09-17T22:17:03.763
Link: CVE-2026-73639
Redhat
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OpenCVE Enrichment
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