Unauthenticated action execution via unmasked frames
Published Jul 22, 2026 · Updated Jul 22, 2026
Improper WebSocket frame validation in Boaz Segev facil.io 0.7.0 through 0.7.4 allows remote attackers to execute one application action. The parser calls websocket_on_protocol_error for a client frame with MASK cleared but continues into opcode dispatch and invokes on_message before teardown. Exposure requires a reachable facil.io WebSocket endpoint; each connection can cause one unauthorized state-changing action defined by the application's callback.
Summary
What happened
Improper WebSocket frame validation in Boaz Segev facil.io 0.7.0 through 0.7.4 allows remote attackers to execute one application action. The parser calls websocket_on_protocol_error for a client frame with MASK cleared but continues into opcode dispatch and invokes on_message before teardown. Exposure requires a reachable facil.io WebSocket endpoint; each connection can cause one unauthorized state-changing action defined by the application's callback.
The record
- CVE
- CVE-2026-16632
- Published
- Jul 22, 2026
- Updated
- Jul 22, 2026
- Vendor
- Boaz Segev
- Product
- facil.io
- Classifications
- CWE-20, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 22, 2026CVE publishedPublication date reported by the CVE source.
- Jul 22, 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=0.7.0
- Affected versionversion=0.7.1
- Affected versionversion=0.7.2
- Affected versionversion=0.7.3
- Affected versionversion=0.7.4
What conditions does exploitation require?
What is affected?
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.
Public exploit references
- WebSocket unmasked-frame callback proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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