CVE intelligence and bounded remediation
CVE-2020-28049 — An issue was discovered in SDDM before 0.19.0
An issue was discovered in SDDM before 0.19.0. It incorrectly starts the X server in a way that - for a short time period - allows local unprivileged users to create a connection to the X server without providing proper authentication. A local attacker can thus access X server display contents and, for example, intercept keystrokes or access the clipboard. This is caused by a race condition during Xauthority file creation.
- Severity
- Medium
- CVSS
- 6.3 (3.1)
- Published
- 2020-11-04
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-362
Affected products
- sddm_project / sddm
- opensuse / leap / 15.1
- opensuse / leap / 15.2
- debian / debian_linux / 9.0
- debian / debian_linux / 10.0
- fedoraproject / fedora / 33
Matched remediation archetype
Race condition, TOCTOU, and lifecycle synchronization
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
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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