CVE-2026-65979: OpenEXR: Out-of-bounds read in HTJ2K decoder from unvalidated chunk header length (PLEN)

Vulnerability summary

CVE-2026-65979 is a medium (CVSS 6.7) Improper Input Validation vulnerability in academysoftwarefoundation openexr. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.2% of scored vulnerabilities.

Timeline

1. 25-08-2026
   PublishedVulnerability first disclosed.
2. 25-08-2026
   Last modifiedVulnerability information updated.

Description

OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. From version 3.4.0 through 3.4.12, the HTJ2K decoder parses a header-length field (PLEN) from a chunk's compressed data but never checks that this value fits within the available buffer before using it. When decoding, it advances the codestream pointer by the attacker-supplied header size and passes the resulting offset and remaining length to the OpenJPH memory-input path, so a crafted value pushes the pointer past the end of the buffer and causes an out-of-bounds read. Because this field comes straight from attacker-controlled EXR chunk data, the flaw is reachable during normal decoding of an untrusted file. This issue is fixed in version 3.4.13.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.