CVE-2026-26981 OpenEXR has heap-buffer-overflow via signed integer underflow in ImfContextInit.cpp
A signed integer underflow in OpenEXR leads to a heap buffer overflow when parsing malformed files, potentially causing crashes or data exposure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-26981?
CVE-2026-26981 is a medium-severity vulnerability in Openexr Openexr, published on 24 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
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.
Weakness: CWE-195
Which versions are affected by CVE-2026-26981?
5 open source packages ship an affected version, including openexr and OpenEXR. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
openexr PyPI | From 3.3.0 | 3.3.7, 3.4.5 |
openexr PyPI | From 3.3.0 | 3.3.7 |
openexr PyPI | From 3.4.0 | 3.4.5 |
OpenEXR PyPI | From 3.3.0 | 3.3.7 |
OpenEXR PyPI | From 3.4.0 | 3.4.5 |
Linux distribution packages (1)
openexr openSUSE:Tumbleweed | All versions | 3.4.5-1.1 |
Products include Openexr Openexr.
How do I fix CVE-2026-26981?
Upgrade openexr to a fixed version for your release line: 3.3.7 or 3.4.5.
Is CVE-2026-26981 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-26981 exists.
Other vulnerabilities in Openexr Openexr
- CVE-2023-5841 OpenEXR Heap Overflow in Scanline Deep Data Parsing
- CVE-2026-41142 OpenEXR is Vulnerable to Integer overflow in ImageChannel::resize leads to heap OOB write via OpenEXRUtil public API
- CVE-2026-42216 OpenEXR: Out-of-bounds read in `IDManifest::init()` during prefix expansion
- CVE-2017-9111 OpenEXR invalid write
- CVE-2017-9113 Memory corruption in n/a
Sources
Also known as GHSA-q6vj-wxvf-5m8c, JLSEC-2026-140, PYSEC-2026-2849, openSUSE-SU-2026:10272-1.