CVE intelligence and bounded remediation
CVE-2024-6409 — A race condition vulnerability was discovered in how signals are handled by OpenSSH's server (sshd)
A race condition vulnerability was discovered in how signals are handled by OpenSSH's server (sshd). If a remote attacker does not authenticate within a set time period, then sshd's SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are not async-signal-safe, for example, syslog(). As a consequence of a successful attack, in the worst case scenario, an attacker may be able to perform a remote code execution (RCE) as an unprivileged user running the sshd server.
- Severity
- High
- CVSS
- 7 (3.1)
- Published
- 2024-07-08
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-364
Affected products
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Matched remediation archetype
Race condition, TOCTOU, and lifecycle synchronization
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Check exposure
- Map concurrent actors, shared state, lock boundaries, signals, callbacks, retries, and check-then-use sequences in the affected path.
- Determine whether untrusted users can influence timing, object names, filesystem state, or repeated state transitions.
- Identify clustered and multi-process behavior that repository-local tests may not represent.
Remediate safely
- Make the sensitive state transition atomic or protect it with a consistently ordered synchronization primitive.
- Perform authorization and invariant checks on the same authoritative object and transaction used for the operation.
- Use unique private resources, safe ownership transfer, and idempotent operations; add deterministic concurrency regression tests.
Authoritative sources
Complete CVE record and remediation plan
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