Cyber Resilience

CVE-2021-36394

CriticalRCE

Published: 06 March 2023

Published
06 March 2023
Modified
06 March 2025
KEV Added
Patch
CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.1165 93.8th percentile
Risk Priority 27 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-36394 is a critical-severity Session Fixation (CWE-384) vulnerability in Moodle Moodle. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 6.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

In Moodle, a remote code execution risk was identified in the Shibboleth authentication plugin.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

moodle
moodle
≤ 3.9.8 · 3.10.0 — 3.10.5 · 3.11.0 — 3.11.1

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-384

Session termination after a set interval shortens the usable lifetime of a fixed session identifier, making successful exploitation of session fixation more difficult.

addresses: CWE-384

Re-authentication typically forces issuance of a new session, limiting the window for exploitation of a previously fixed session identifier.

addresses: CWE-384

Enforces proper session ID generation and binding, preventing fixation of a known session token.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Validates inputs used in dynamic code generation to block injected directives.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

References