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NVD / CVE Program· CNA GitHub_M

CVE-2026-27591: Winter: Privilege escalation by authenticated backend users

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.68% (FIRST EPSS); higher than 52.7% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: wintercms winter 1.0.477.

Low priority for now. Upgrade to wintercms winter 1.0.477 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

CriticalCVSS 9.9 · v3.1—No exploit Fix available
Published
Mar 11, 2026
Updated
Jun 17, 2026
EPSS
0.6% · 52th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
10.0
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-27591

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
wintercmswinter

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • wintercms winterbefore 1.0.477
  • wintercms winter1.1.0 and later · before 1.1.12
  • wintercms winter1.2.0 and later · before 1.2.12

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • wintercms winter

    • >= 1.2.0, < 1.2.12, >= 1.1.0, < 1.1.12, < 1.0.477affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Packagistwinter/wn-backend-modulefrom 1.1.0 · before 1.1.121.1.12
Packagistwinter/wn-backend-modulefrom 1.2.0 · before 1.2.121.2.12
Packagistwinter/wn-backend-modulebefore 1.0.4771.0.477

Same product

wintercms: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-39357Winter vulnerable to Prototype Pollution in Snowboard framework
    39Monitor
  • CVE-2026-79774Winter CMS before 1.2.13 Twig Sandbox Escape via SecurityPolicy
    37Monitor
  • CVE-2024-54149Winter CMS Modules allows a sandbox bypass in Twig templates leading to data modification and deletion
    33Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2024-29686Mar 29, 2024 · Server-side Template Injection (SSTI) vulnerability in Winter CMS v.1.2.3 allows a remote attacker to execute arbitrary code via a crafted p
    29Monitor
  • ← EarlierCVE-2026-22254Feb 6, 2026 · Winter Affected by Stored Cross-Site Scripting (XSS) in Asset Manager
    14Monitor
  • Later →CVE-2026-79773Aug 25, 2026 · Winter CMS before 1.2.13 Local File Inclusion via JavaScript
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
wintercms winter1.0.477 · descriptionVendor (CNA)
Packagist:winter/wn-backend-module1.0.477Package registry (OSV)
Packagist:winter/wn-backend-module1.1.12Package registry (OSV)
Packagist:winter/wn-backend-module1.2.12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-54256168 days apartWinter: Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-284 · Improper Access Control

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records