CVE-2026-26981

OpenEXR has heap-buffer-overflow via signed integer underflow in ImfContextInit.cpp

MEDIUM
6.5
CVSS Score
Published: February 24, 2026 at 02:26 AM UTC
Updated: June 17, 2026 at 10:26 AM UTC
2 products affected across 2 vendorsOpenexrOpenexr

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.3.0 ≤ v < 3.3.73.4.0 ≤ v < 3.4.5
v < 3.3.7v < 3.4.5
Affected range stops below 3.3.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.4.5, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-195

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