ImageMagick BlobStream Forward-Seek Under-Allocation

ImageMagick is free and open-source software used for editing and manipulating digital images. ImageMagick versions lower than 14.8.2 include insecure functions: SeekBlob(), which permits advancing the stream offset beyond the current end without increasing capacity, and WriteBlob(), which then expands by quantum + length (amortized) instead of offset + length, and copies to data + offset. When offset ≫ extent, the copy targets memory beyond the allocation, producing a deterministic heap write on 64-bit builds. No 2⁶⁴ arithmetic wrap, external delegates, or policy settings are required. This is fixed in version 14.8.2.

Source published

5 Sep 2025 21:16:02 UTC

Source modified

3 Nov 2025 18:13:45 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 3.8 CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L