CVE-2026-55373

OpenEXR: OpenEXRUtil SampleCountChannel endEdit() can loop forever on UINT_MAX sample counts

MEDIUM
6.2
CVSS Score
Published: August 25, 2026 at 12:39 AM UTC
Updated: October 12, 2026 at 03:10 PM UTC
1 product affected across 1 vendorOpenexr

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Severity
MEDIUM6.2
Exploit prediction
EPSS 0.2%
SSVC
PoC

Description

OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. Versions prior to 3.2.10, 3.3.12, and 3.4.13 contain an infinite-loop vulnerability in SampleCountChannel. The helper roundListSizeUp() rounds a sample-list size up to the next power of two using repeated unsigned left shifts, which terminates for normal values but fails for UINT_MAX: the sequence reaches 0x80000000, and the next left shift wraps the 32-bit value to 0. Because 0 remains less than UINT_MAX, the loop never progresses and never exits. The bug is reachable through public OpenEXRUtil APIs, either by editing the sample-count buffer through SampleCountChannel::Edit (whose destructor calls endEdit()) or by calling SampleCountChannel::set(x, y, UINT_MAX) on a valid pixel. This issue has been fixed in versions 3.2.10, 3.3.12, and 3.4.13.

Affected

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

v < 3.2.10>= 3.3.0, < 3.3.12>= 3.4.0, < 3.4.13
Affected range stops below 3.2.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.3.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.4.13, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

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

CVSS

6.2MEDIUMGitHub_M
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-190CWE-400CWE-835

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