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Fencer Vulns
critical 10.0

CVE-2026-27591 json

Winter: Privilege escalation by authenticated backend users

published 2026-03-11 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-11406 , GHSA-pgpf-m8m4-6cg6

cvss
10.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 56%
public exploits
0
none known

Summary

Winter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.0.477, 1.1.12, and 1.2.12, Winter CMS allowed authenticated backend users to escalate their accounts level of access to the system by modifying the roles / permissions assigned to their account through specially crafted requests to the backend while logged in. To actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access. This vulnerability is fixed in 1.0.477, 1.1.12, and 1.2.12.

Patch / fix

  • packagist winter/wn-backend-module 1.0.477, 1.1.12, 1.2.12
  • wintercms winter 1.0.477, 1.1.12, 1.2.12

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
7 mo ago

Exploit prediction

0.78% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
GitHub 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
packagist winter/wn-backend-module
>=1.2.0, <1.2.12
>=1.1.0, <1.1.12
<1.0.477
1.2.12
1.1.12
1.0.477

Affected products

  • wintercms winter

Classification

Weakness
  • CWE-284 Improper Access Control
  • CWE-639 Authorization Bypass Through User-Controlled Key
  • CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.