Code execution via HTJ2K decoder counter wraparound
Published Apr 1, 2026 · Updated Apr 1, 2026
Heap-buffer overflow in OpenEXR 3.4.0 through 3.4.6 allows attackers to execute code via a crafted HTJ2K-compressed EXR file. In internal_ht.cpp, ht_undo_impl copies decompressed samples with a signed 16-bit loop counter while comparing it with an unbounded 32-bit channel width; at 32768 pixels the counter wraps negative and writes past the heap buffer. Exploitation requires an application to decode the file and can corrupt process memory, crash the decoder, or execute code with that application's privileges.
Summary
What happened
Heap-buffer overflow in OpenEXR 3.4.0 through 3.4.6 allows attackers to execute code via a crafted HTJ2K-compressed EXR file. In internal_ht.cpp, ht_undo_impl copies decompressed samples with a signed 16-bit loop counter while comparing it with an unbounded 32-bit channel width; at 32768 pixels the counter wraps negative and writes past the heap buffer. Exploitation requires an application to decode the file and can corrupt process memory, crash the decoder, or execute code with that application's privileges.
The record
- CVE
- CVE-2026-34545
- Published
- Apr 1, 2026
- Updated
- Apr 1, 2026
- Vendor
- Academy Software Foundation
- Product
- OpenEXR
- Classifications
- CWE-1284, CWE-190, CWE-122, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 1, 2026CVE publishedPublication date reported by the CVE source.
- Apr 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 3.4.0, < 3.4.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- HTJ2K width-32768 decoder proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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