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.
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.
Metrics
Affected Vendors & Products
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Advisories
No advisories yet.
Fixes
Solution
Upgrade to Imager-File-PNG 1.004 or later, or to Imager 1.035 or later if the bundled copy is in use.
Workaround
No workaround given by the vendor.
References
History
Fri, 18 Sep 2026 01:30:00 +0000
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Thu, 17 Sep 2026 21:30:00 +0000
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| 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 | |
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-09-18T00:18:32.862Z
Reserved: 2026-08-13T12:51:42.912Z
Link: CVE-2026-73639
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T22:17:03.763
Modified: 2026-09-18T01:16:56.010
Link: CVE-2026-73639
Redhat
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OpenCVE Enrichment
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Weaknesses