Vulnerability · Published Feb 24, 2026 · Assigned by GitHub_M
CVE-2026-26981OpenEXR has heap-buffer-overflow via signed integer underflow in ImfContextInit.cpp
Medium 6.5
In plain English
A medium-severity security flaw in openexr from AcademySoftwareFoundation. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. In versions 3.3.0 through 3.3.6 and 3.4.0 through 3.4.4, a heap-buffer-overflow (OOB read) occurs in the `istream_nonparallel_read` function in `ImfContextInit.cpp` when parsing a malformed EXR file through a memory-mapped `IStream`. A signed integer subtraction produces a negative value that is implicitly converted to `size_t`, resulting in a massive length being passed to `memcpy`. Versions 3.3.7 and 3.4.5 contain a patch.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | openexr | 3.3.7 | GHSA-q6vj-wxvf-5m8c |
| PyPI | openexr | 3.4.5 | GHSA-q6vj-wxvf-5m8c |
| PyPI | openexr | 3.3.7, 3.4.5 | PYSEC-2026-2849 |
| Ubuntu:24.04:LTS | openexr | no fix listed | UBUNTU-CVE-2026-26981 |
| Ubuntu:25.10 | openexr | no fix listed | UBUNTU-CVE-2026-26981 |
| Ubuntu:26.04 | openexr | no fix listed | UBUNTU-CVE-2026-26981 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AcademySoftwareFoundation | openexr | >= 3.3.0, < 3.3.7>= 3.4.0, < 3.4.5 |
Weakness: CWE-195 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
References
- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-q6vj-wxvf-5m8c x_refsource_CONFIRM
- https://github.com/AcademySoftwareFoundation/openexr/commit/6bb2ddf1068573d073edf81270a015b38cc05cef x_refsource_MISC
- https://github.com/AcademySoftwareFoundation/openexr/commit/d2be382758adc3e9ab83a3de35138ec28d93ebd8 x_refsource_MISC