How severe is CVE-2025-53021?

CVE-2025-53021 has a CVSS 3.x base score of 4.2, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-53021 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-53021?

CVE-2025-53021 affects Moodle. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-53021?

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

Does CVE-2025-53021 have an EU (EUVD) identifier?

Yes. CVE-2025-53021 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-19060.

When was CVE-2025-53021 published?

CVE-2025-53021 was published on 2025-06-24 and last updated on 2026-06-17.

CVE-2025-53021

CVE-2025-53021 is a medium-severity vulnerability in Moodle with a CVSS 3.x base score of 4.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-384.

Key facts

Severity: Medium (CVSS 3.x base score 4.2)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-19060
Weakness: CWE-384
Affected product: Moodle
Published: 2025-06-24
Last modified: 2026-06-17

Description

A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter. The sesskey can be obtained without authentication and reused within the OAuth2 login flow, resulting in the victim's session being linked to the attacker's. Successful exploitation results in full account takeover. According to the Moodle Releases page, "Bug fixes for security issues in 3.11.x ended 11 December 2023." NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

Frequently asked questions

What is CVE-2025-53021?: A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter. The sesskey can be obtained without authentication and reused within the OAuth2 login flow, resulting in the victim's session being linked to the attacker's. Successful exploitation results in full account takeover. According to the Moodle Releases page, "Bug fixes for security issues in 3.11.x ended 11 December 2023." NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
How severe is CVE-2025-53021?: CVE-2025-53021 has a CVSS 3.x base score of 4.2, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-53021 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-53021?: CVE-2025-53021 affects Moodle. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-53021?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-53021 have an EU (EUVD) identifier?: Yes. CVE-2025-53021 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-19060.
When was CVE-2025-53021 published?: CVE-2025-53021 was published on 2025-06-24 and last updated on 2026-06-17.

References

Affected products (1)

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

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