Code execution via unchecked tdelta array index
Published Jan 8, 2024 · Updated Nov 4, 2025
Heap out-of-bounds write in GTKWave 3.3.115 allows attackers to execute arbitrary code by convincing a victim to open a crafted FST file. In fstReaderIterBlocks2, a file-derived varint becomes tdelta and indexes tc_head without validation when signal_lens is zero, permitting a heap write beyond the allocated array. Exploitation requires user interaction with the malicious waveform file and can execute code in the affected process.
Summary
What happened
Heap out-of-bounds write in GTKWave 3.3.115 allows attackers to execute arbitrary code by convincing a victim to open a crafted FST file. In fstReaderIterBlocks2, a file-derived varint becomes tdelta and indexes tc_head without validation when signal_lens is zero, permitting a heap write beyond the allocated array. Exploitation requires user interaction with the malicious waveform file and can execute code in the affected process.
The record
- CVE
- CVE-2023-35996
- Published
- Jan 8, 2024
- Updated
- Nov 4, 2025
- Vendor
- GTKWave
- Product
- GTKWave
- Classifications
- CWE-129, T1204.002, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 8, 2024CVE publishedPublication date reported by the CVE source.
- Nov 4, 2025Record 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=3.3.115
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
- Cisco Talos crafted FST proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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