CVE-2026-54721

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 64% 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
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

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

Silverstripe UserForms provides a visual form builder for the Silverstripe CMS. From 6.0.0 until 6.4.9, 7.0.7, and 7.1.1, the userform email recipient subject field in the CMS accepts a specially crafted payload that can be interpreted as executable server-side code. An authenticated CMS user with permission to configure a UserForms email recipient can use the subject field to run arbitrary code on the server, compromising confidentiality, integrity, and availability. This issue is fixed in versions 6.4.9, 7.0.7, and 7.1.1.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

August 27, 2026

Last Modified

September 9, 2026

Advisory Details (8)

Auto-updated Aug 27, 2026
Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available

Remote code execution via userforms email subject · Advisory · silverstripe/silverstripe-userforms · GitHub

https://github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6
github_release Patch Available

7.1.1

Patch available: silverstripe/silverstripe-userforms 7.1.1

https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.1.1
github_release Patch Available

7.0.7

Patch available: silverstripe/silverstripe-userforms 7.0.7

https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.0.7
github_release Patch Available

6.4.9

Patch available: silverstripe/silverstripe-userforms 6.4.9

https://github.com/silverstripe/silverstripe-userforms/releases/tag/6.4.9
github_pr Patch Available

[CVE-2026-54721] Prevent RCE via email recipient subject

Patch available: silverstripe/silverstripe-userforms 6.4.9 (PR #1442 merged 2026-06-24)

https://github.com/silverstripe/silverstripe-userforms/pull/1442
github_pr Patch Available

[CVE-2026-54721] Prevent RCE via email recipient subject

Patch available: silverstripe/silverstripe-userforms 7.0.7 (PR #1441 merged 2026-06-24)

https://github.com/silverstripe/silverstripe-userforms/pull/1441
github_commit Patch Available

commit c55494ad7c71 (silverstripe/silverstripe-userforms)

Patch available: silverstripe/silverstripe-userforms 6.4.9 (contains commit c55494ad7c71)

https://github.com/silverstripe/silverstripe-userforms/commit/c55494ad7c717b199a3c1663b43a54db5d95604c
github_commit Patch Available

commit 23c069866900 (silverstripe/silverstripe-userforms)

Patch available: silverstripe/silverstripe-userforms 7.0.7 (contains commit 23c069866900)

https://github.com/silverstripe/silverstripe-userforms/commit/23c069866900c19b499bfa997d1e251e97491702

Vendor Advisories for CVE-2026-54721(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
silverstripe/userforms7.1.07.1.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 44× 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. 2026-09-19 01:43 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 01:18 UTCEG score recompute
  4. 2026-09-17 19:31 UTCEPSS rescore
  5. 2026-09-17 00:31 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 12:18 UTCEG score recompute
  8. 2026-09-16 05:15 UTCEPSS rescore
  9. 2026-09-15 11:51 UTCEG score recompute
  10. 2026-09-15 03:11 UTCEPSS rescore
  11. 2026-09-13 22:57 UTCEG score recompute
  12. 2026-09-13 16:47 UTCEPSS rescore
  13. 2026-09-12 22:32 UTCEG score recompute
  14. 2026-09-11 22:07 UTCEG score recompute
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-11 09:54 UTCEG score recompute
  17. 2026-09-10 21:41 UTCEG score recompute
  18. 2026-09-10 09:35 UTCEPSS rescore
  19. 2026-09-09 00:40 UTCEG score recompute
  20. 2026-09-08 22:01 UTCEPSS rescore
  21. 2026-09-08 03:19 UTCEG score recompute
  22. 2026-09-07 16:01 UTCEPSS rescore
  23. 2026-09-07 01:09 UTCEG score recompute
  24. 2026-09-06 13:47 UTCEPSS rescore
  25. 2026-09-06 00:42 UTCEG score recompute
Show 19 more
  1. 2026-09-05 00:14 UTCEG score recompute
  2. 2026-09-04 12:01 UTCEG score recompute
  3. 2026-09-04 05:06 UTCEPSS rescore
  4. 2026-09-02 22:58 UTCEG score recompute
  5. 2026-09-02 14:12 UTCEPSS rescore
  6. 2026-09-01 22:29 UTCEG score recompute
  7. 2026-09-01 13:54 UTCEPSS rescore
  8. 2026-09-01 10:16 UTCEG score recompute
  9. 2026-09-01 04:40 UTCEPSS rescore
  10. 2026-08-30 21:37 UTCEG score recompute
  11. 2026-08-30 19:17 UTCEPSS rescore
  12. 2026-08-30 09:24 UTCEG score recompute
  13. 2026-08-30 01:22 UTCEPSS rescore
  14. 2026-08-29 08:57 UTCEG score recompute
  15. 2026-08-28 21:41 UTCEPSS rescore
  16. 2026-08-28 20:43 UTCEG score recompute
  17. 2026-08-28 19:47 UTCEG score recompute
  18. 2026-08-27 20:27 UTCEG score recompute
  19. 2026-08-27 17:23 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-54721?
CVE-2026-54721 is a high vulnerability published on August 27, 2026. Silverstripe UserForms provides a visual form builder for the Silverstripe CMS. From 6.0.0 until 6.4.9, 7.0.7, and 7.1.1, the userform email recipient subject field in the CMS accepts a specially crafted payload that can be interpreted as executable server-side code. An authenticated CMS user with…
When was CVE-2026-54721 disclosed?
CVE-2026-54721 was first published in the National Vulnerability Database on August 27, 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-2026-54721 actively exploited?
CVE-2026-54721 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 64.5% of all scored CVEs.
What is the CVSS score of CVE-2026-54721?
CVE-2026-54721 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-54721?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54721, 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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