PT-2026-33907 · Academy Software Foundation · Openexr

Published

2026-04-21

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Updated

2026-04-21

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CVE-2026-39886

CVSS v3.1

5.3

Medium

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. Versions 3.4.0 through 3.4.9 have a signed integer overflow vulnerability in OpenEXR's HTJ2K (High-Throughput JPEG 2000) decompression path. The ht undo impl() function in src/lib/OpenEXRCore/internal ht.cpp accumulates a bytes-per-line value (bpl) using a 32-bit signed integer with no overflow guard. A crafted EXR file with 16,385 FLOAT channels at the HTJ2K maximum width of 32,767 causes bpl to overflow INT MAX, producing undefined behavior confirmed by UBSan. On an allocator-permissive host where the required ~64 GB allocation succeeds, the wrapped negative bpl value would subsequently be used as a per-scanline pointer advance, which would produce a heap out-of-bounds write. On a memory-constrained host, the allocation fails before ht undo impl() is entered. This is the second distinct integer overflow in ht undo impl(). CVE-2026-34545 addressed a different overflow in the same function — the int16 t p pixel-loop counter at line ~302 that overflows when iterating over channels whose width exceeds 32,767. The CVE-2026-34545 fix did not touch the int bpl accumulator at line 211, which is the subject of this advisory. The bpl accumulator was also not addressed by any of the 8 advisories in the 2026-04-05 v3.4.9 release batch. This finding is structurally identical to CVE-2026-34588 (PIZ wcount*nx overflow in internal piz.c) and should be remediated with the same pattern. The CVE-2026-34588 fix did not touch internal ht.cpp. Version 3.4.10 contains a remediation that addresses the vulnerability in internal ht.cpp.

Fix

Integer Overflow

Weakness Enumeration

CWE-190

Related Identifiers

CVE-2026-39886

Affected Products

Openexr