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Fencer Vulns
critical 9.8

CVE-2021-27903 json

Craft CMS Remote Code Injection

published 2021-06-30 5 y ago modified 2026-06-17 4 mo ago also GHSA-x2j7-6hxm-87p3 , EUVD-2021-1499

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.8%
EPSS 2.8% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

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).

Patch / fix

  • packagist craftcms/cms 3.6.7
  • craftcms craft_cms 3.6.7

Exploit prediction

2.82% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
packagist craftcms/cms
<3.6.7
3.6.7

Classification

Weakness
  • CWE-862 Missing Authorization
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.