Memory corruption via stale CBOR buffer offset
Published Aug 24, 2026 · Updated Aug 24, 2026
Out-of-bounds write in Warmcat libwebsockets 4.5.0 allows remote attackers to corrupt memory via crafted LECP CBOR input. In lecp_parse, a rejecting literal-CBOR callback leaves cbor_pos at the 64-byte buffer limit, so a retry writes the next attacker-controlled byte into adjacent item storage before bounds handling. LECP raw-CBOR reporting must be enabled and its callback must reject a full buffer; reported outcomes include data disclosure, state corruption, and process crash.
Summary
What happened
Out-of-bounds write in Warmcat libwebsockets 4.5.0 allows remote attackers to corrupt memory via crafted LECP CBOR input. In lecp_parse, a rejecting literal-CBOR callback leaves cbor_pos at the 64-byte buffer limit, so a retry writes the next attacker-controlled byte into adjacent item storage before bounds handling. LECP raw-CBOR reporting must be enabled and its callback must reject a full buffer; reported outcomes include data disclosure, state corruption, and process crash.
The record
- CVE
- CVE-2026-78161
- Published
- Aug 24, 2026
- Updated
- Aug 24, 2026
- Vendor
- libwebsockets
- Product
- libwebsockets
- Classifications
- CWE-787, CWE-119, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 24, 2026CVE publishedPublication date reported by the CVE source.
- Aug 24, 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=4.5.0
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
- libwebsockets LECP CBOR position out-of-bounds write PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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