How severe is CVE-2021-40691?

CVE-2021-40691 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-40691 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40691?

CVE-2021-40691 affects Moodle. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40691?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-40691 published?

CVE-2021-40691 was published on 2022-09-29 and last updated on 2026-06-17.

CVE-2021-40691

CVE-2021-40691 is a medium-severity vulnerability in Moodle with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Moodle
Published: 2022-09-29
Last modified: 2026-06-17

Description

A session hijack risk was identified in the Shibboleth authentication plugin.

Frequently asked questions

What is CVE-2021-40691?: A session hijack risk was identified in the Shibboleth authentication plugin.
How severe is CVE-2021-40691?: CVE-2021-40691 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-40691 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40691?: CVE-2021-40691 affects Moodle. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40691?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-40691 published?: CVE-2021-40691 was published on 2022-09-29 and last updated on 2026-06-17.

References

https://bugzilla.redhat.com/show_bug.cgi?id=2043411

Affected products (1)

cpe:2.3:a:moodle:moodle:*:*:*:*:*:*:*:*

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