CVE-2026-54256

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Winter CMS is a content management system built on the Laravel PHP framework. In versions up to and including 1.2.12, the backend FileUpload form widget trusted an attacker-controlled file_id POST parameter when resolving the attachment it operates on, allowing an authenticated backend user to read and modify attachment records belonging to other users or records. The widget's getFileRecord() lookup resolved the posted id against the global system_files table without verifying that the file belonged to the widget's own relation, parent record, or deferred-binding session. Because all attachments share a single File model and table and attachment ids are sequential integers that are easily enumerated, a user reaching any form with a fileupload field, including the built-in My Account avatar field that requires no specific permission, could target arbitrary attachments to modify their title and description via onSaveAttachmentConfig and change their sort order via onSortAttachments, which passed posted ids straight to an unscoped update. CSRF tokens remain enforced, so exploitation requires a valid authenticated backend session with any level of access. This issue is fixed in version 1.2.13.

CVSS v3
5.4
EG Score
5.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

August 20, 2026

Last Modified

September 9, 2026

Advisory Details (2)

Auto-updated Aug 26, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Authenticated IDOR in backend FileUpload widget allows cross-user access to attachment metadata · Advisory · wintercms/winter · GitHub

https://github.com/wintercms/winter/security/advisories/GHSA-3277-h8g9-qj5f
github_commit Patch Available

commit 9cb0ae5f9d83 (wintercms/winter)

Patch available: wintercms/winter v1.2.13 (contains commit 9cb0ae5f9d83)

https://github.com/wintercms/winter/commit/9cb0ae5f9d837db141ab111c6a7de8eed9603d25

Vendor Advisories for CVE-2026-54256(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
winter/wn-backend-modulev1.0.473 ... v1.2.9 (26 versions)1.2.13—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 39× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 21:38 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 21:19 UTCEG score recompute
  4. 2026-09-17 19:31 UTCEPSS rescore
  5. 2026-09-16 19:44 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 19:47 UTCEG score recompute
  9. 2026-09-13 20:17 UTCEG score recompute
  10. 2026-09-13 16:47 UTCEPSS rescore
  11. 2026-09-12 20:34 UTCEG score recompute
  12. 2026-09-11 20:51 UTCEG score recompute
  13. 2026-09-10 21:08 UTCEG score recompute
  14. 2026-09-10 09:35 UTCEPSS rescore
  15. 2026-09-09 01:55 UTCEG score recompute
  16. 2026-09-08 22:01 UTCEPSS rescore
  17. 2026-09-07 20:16 UTCEG score recompute
  18. 2026-09-07 16:01 UTCEPSS rescore
  19. 2026-09-06 20:34 UTCEG score recompute
  20. 2026-09-06 13:47 UTCEPSS rescore
  21. 2026-09-05 20:49 UTCEG score recompute
  22. 2026-09-04 21:07 UTCEG score recompute
  23. 2026-09-04 05:06 UTCEPSS rescore
  24. 2026-09-02 21:08 UTCEG score recompute
  25. 2026-09-02 14:12 UTCEPSS rescore
Show 14 more
  1. 2026-09-01 18:06 UTCEG score recompute
  2. 2026-09-01 13:54 UTCEPSS rescore
  3. 2026-09-01 04:40 UTCEPSS rescore
  4. 2026-08-31 18:15 UTCEG score recompute
  5. 2026-08-30 19:17 UTCEPSS rescore
  6. 2026-08-30 17:34 UTCEG score recompute
  7. 2026-08-30 01:22 UTCEPSS rescore
  8. 2026-08-29 17:51 UTCEG score recompute
  9. 2026-08-28 21:41 UTCEPSS rescore
  10. 2026-08-27 17:38 UTCEG score recompute
  11. 2026-08-27 17:17 UTCEG score recompute
  12. 2026-08-27 14:25 UTCEPSS rescore
  13. 2026-08-26 18:24 UTCEG score recompute
  14. 2026-08-20 18:42 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-54256?
CVE-2026-54256 is a medium vulnerability published on August 20, 2026. Winter CMS is a content management system built on the Laravel PHP framework. In versions up to and including 1.2.12, the backend FileUpload form widget trusted an attacker-controlled fileid POST parameter when resolving the attachment it operates on, allowing an authenticated backend user to read…
When was CVE-2026-54256 disclosed?
CVE-2026-54256 was first published in the National Vulnerability Database on August 20, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54256 actively exploited?
CVE-2026-54256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 96.0% of all scored CVEs.
What is the CVSS score of CVE-2026-54256?
CVE-2026-54256 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-54256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54256, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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