How severe is CVE-2021-27903?

CVE-2021-27903 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27903 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27903?

CVE-2021-27903 affects Craftcms Craft Cms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27903?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-27903 published?

CVE-2021-27903 was published on 2021-06-30 and last updated on 2026-06-17.

CVE-2021-27903

CVE-2021-27903 is a critical-severity vulnerability in Craftcms Craft Cms with a CVSS 3.x base score of 9.8. 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-862.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-862
Affected product: Craftcms Craft Cms
Published: 2021-06-30
Last modified: 2026-06-17

Description

An issue was discovered in Craft CMS before 3.6.7. In some circumstances, a potential Remote Code Execution vulnerability existed on sites that did not restrict administrative changes (if an attacker were somehow able to hijack an administrator's session).

Frequently asked questions

What is CVE-2021-27903?: An issue was discovered in Craft CMS before 3.6.7. In some circumstances, a potential Remote Code Execution vulnerability existed on sites that did not restrict administrative changes (if an attacker were somehow able to hijack an administrator's session).
How severe is CVE-2021-27903?: CVE-2021-27903 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27903 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27903?: CVE-2021-27903 affects Craftcms Craft Cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27903?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-27903 published?: CVE-2021-27903 was published on 2021-06-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:craftcms:craft_cms:*:*:*:*:*:*:*:*

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