Authenticated SFTP channel hang via extended data loop
Published Jul 2, 2026 · Updated Jul 2, 2026
An infinite loop in Erlang/OTP ssh_sftpd allows remote authenticated users to hang SFTP channels via extended channel data. The handle_data/4 catch-all clause tail-calls itself with unchanged arguments when a nonzero data type arrives with an empty pending buffer and a payload no larger than the packet limit. An authenticated SFTP session is required; each trapped process consumes CPU and accumulates queued messages, while file contents and credentials remain inaccessible.
Summary
What happened
An infinite loop in Erlang/OTP ssh_sftpd allows remote authenticated users to hang SFTP channels via extended channel data. The handle_data/4 catch-all clause tail-calls itself with unchanged arguments when a nonzero data type arrives with an empty pending buffer and a payload no larger than the packet limit. An authenticated SFTP session is required; each trapped process consumes CPU and accumulates queued messages, while file contents and credentials remain inaccessible.
The record
- CVE
- CVE-2026-54886
- Published
- Jul 2, 2026
- Updated
- Jul 2, 2026
- Vendor
- Erlang
- Product
- Erlang/OTP
- Classifications
- CWE-400, CWE-835, CAPEC-130, T1499.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 2, 2026CVE publishedPublication date reported by the CVE source.
- Jul 2, 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?
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- Affected versionversion=17.0 <* changes=[{"at":"29.0.3","status":"unaffected"},{"at":"28.5.0.3","status":"unaffected"},{"at":"27.3.4.14","status":"unaffected"}]
- Affected versionversion=3.0.1 <* changes=[{"at":"6.0.2","status":"unaffected"},{"at":"5.5.2.2","status":"unaffected"},{"at":"5.2.11.9","status":"unaffected"}]
- Affected versionversion=84adefa3318eef8631bf25cd233246a86eea18cd <eaf9550b8ad4738b81149d3f617102d980c6dd18
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Technologies
Your stack
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Your stack
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