CVE intelligence and bounded remediation
CVE-2018-12029 — Phusion Passenger security vulnerability
A race condition in the nginx module in Phusion Passenger 3.x through 5.x before 5.3.2 allows local escalation of privileges when a non-standard passenger_instance_registry_dir with insufficiently strict permissions is configured. Replacing a file with a symlink after the file was created, but before it was chowned, leads to the target of the link being chowned via the path. Targeting sensitive files such as root's crontab file allows privilege escalation.
- Severity
- High
- CVSS
- 7 (3.0)
- Published
- 2018-06-17
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-362
Affected products
- phusion / passenger
- debian / debian_linux / 8.0
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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