CVE-2026-55791

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 62% 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
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: None knownExposed: 0

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

Craft CMS is a content management system (CMS). Versions 4.0.0-RC1 and above, prior to 4.18.0 and 5.0.0-RC1, and above, prior to 5.10.0, are vulnerable to Server-Side Request Forgery (SSRF) and Arbitrary JavaScript Injection through the /actions/app/resource-js endpoint. By exploiting the default permissive trustedHosts configuration, an attacker can poison the Host or X-Forwarded-Host header to manipulate the application’s $baseUrl. This bypasses the endpoint’s internal URL validation, forcing the backend Guzzle client to fetch a malicious payload from an attacker-controlled server and reflect it to the client with a Content-Type: application/javascript header. The vulnerability manifests when assetManager.cacheSourcePaths is set to false. This issue has been fixed in versions 4.18.0 and 5.10.0.

CVSS v3
6.9
EG Score
6.9(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: 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
Severity69% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
38%
KEV
Not listed

Published

June 19, 2026

Last Modified

July 2, 2026

Advisory Details (2)

Auto-updated Jul 3, 2026
Patch available. Sources: github_pr, github.
github Patch Available

Blind SSRF and Arbitrary JavaScript Injection via Host Header Poisoning in actionResourceJs · Advisory · craftcms/cms · GitHub

https://github.com/craftcms/cms/security/advisories/GHSA-c55v-343g-5xff
github_pr Patch Available

Enforce appended script ordering

Patch available: craftcms/cms 4.18.0 (PR #18559 merged 2026-04-21)

https://github.com/craftcms/cms/pull/18559

Vendor Advisories for CVE-2026-55791(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
craftcms/cms4.0.0 ... 4.9.7 (249 versions)4.18—

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 47× 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. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-25 01:21 UTCEG score recompute
  3. 2026-08-24 00:28 UTCEG score recompute
  4. 2026-08-23 00:19 UTCEPSS rescore
  5. 2026-08-22 23:33 UTCEG score recompute
  6. 2026-08-21 23:49 UTCEPSS rescore
  7. 2026-08-21 09:26 UTCEG score recompute
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-20 07:59 UTCEG score recompute
  10. 2026-08-19 17:04 UTCEPSS rescore
  11. 2026-08-19 05:55 UTCEG score recompute
  12. 2026-08-18 13:48 UTCEPSS rescore
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-17 03:16 UTCEG score recompute
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-16 02:24 UTCEG score recompute
  17. 2026-08-16 02:14 UTCEPSS rescore
  18. 2026-08-15 01:32 UTCEG score recompute
  19. 2026-08-15 01:30 UTCEPSS rescore
  20. 2026-08-14 00:40 UTCEG score recompute
  21. 2026-08-13 22:00 UTCEPSS rescore
  22. 2026-08-12 23:48 UTCEG score recompute
  23. 2026-08-12 13:51 UTCEPSS rescore
  24. 2026-08-11 22:56 UTCEG score recompute
  25. 2026-08-11 00:00 UTCEPSS rescore
Show 63 more
  1. 2026-08-09 21:13 UTCEG score recompute
  2. 2026-08-09 13:46 UTCEPSS rescore
  3. 2026-08-08 20:22 UTCEG score recompute
  4. 2026-08-08 16:37 UTCEPSS rescore
  5. 2026-08-07 19:30 UTCEG score recompute
  6. 2026-08-06 18:38 UTCEG score recompute
  7. 2026-08-06 13:47 UTCEPSS rescore
  8. 2026-08-05 19:17 UTCEPSS rescore
  9. 2026-08-04 15:18 UTCEG score recompute
  10. 2026-08-04 15:10 UTCEPSS rescore
  11. 2026-08-04 10:39 UTCEPSS rescore
  12. 2026-08-02 05:53 UTCEG score recompute
  13. 2026-08-02 02:27 UTCEPSS rescore
  14. 2026-08-01 05:01 UTCEG score recompute
  15. 2026-08-01 04:16 UTCEPSS rescore
  16. 2026-07-31 03:47 UTCEG score recompute
  17. 2026-07-30 16:28 UTCEPSS rescore
  18. 2026-07-30 02:54 UTCEG score recompute
  19. 2026-07-30 01:30 UTCEPSS rescore
  20. 2026-07-29 01:33 UTCEG score recompute
  21. 2026-07-28 15:37 UTCEPSS rescore
  22. 2026-07-27 18:02 UTCEG score recompute
  23. 2026-07-26 16:47 UTCEG score recompute
  24. 2026-07-26 14:54 UTCEPSS rescore
  25. 2026-07-25 14:18 UTCEPSS rescore
  26. 2026-07-24 14:18 UTCEPSS rescore
  27. 2026-07-23 14:18 UTCEPSS rescore
  28. 2026-07-23 03:20 UTCEG score recompute
  29. 2026-07-22 14:08 UTCEPSS rescore
  30. 2026-07-21 15:25 UTCEPSS rescore
  31. 2026-07-20 17:08 UTCEPSS rescore
  32. 2026-07-19 14:31 UTCEPSS rescore
  33. 2026-07-19 14:31 UTCEPSS rescore
  34. 2026-07-19 02:29 UTCEPSS rescore
  35. 2026-07-18 10:04 UTCEPSS rescore
  36. 2026-07-16 17:03 UTCEPSS rescore
  37. 2026-07-15 16:57 UTCEPSS rescore
  38. 2026-07-15 16:57 UTCEPSS rescore
  39. 2026-07-15 02:00 UTCEPSS rescore
  40. 2026-07-15 02:00 UTCEPSS rescore
  41. 2026-07-13 22:31 UTCEPSS rescore
  42. 2026-07-13 06:13 UTCEPSS rescore
  43. 2026-07-13 06:13 UTCEPSS rescore
  44. 2026-07-12 05:46 UTCEPSS rescore
  45. 2026-07-11 08:27 UTCEPSS rescore
  46. 2026-07-11 08:27 UTCEPSS rescore
  47. 2026-07-09 19:10 UTCEPSS rescore
  48. 2026-07-09 19:10 UTCEPSS rescore
  49. 2026-07-08 15:16 UTCEPSS rescore
  50. 2026-07-08 15:16 UTCEPSS rescore
  51. 2026-07-07 13:46 UTCEPSS rescore
  52. 2026-07-07 13:46 UTCEPSS rescore
  53. 2026-07-06 16:27 UTCEPSS rescore
  54. 2026-07-06 16:27 UTCEPSS rescore
  55. 2026-07-06 02:23 UTCEPSS rescore
  56. 2026-07-06 02:23 UTCEPSS rescore
  57. 2026-07-05 02:31 UTCEPSS rescore
  58. 2026-07-05 02:30 UTCEPSS rescore
  59. 2026-07-04 06:31 UTCEPSS rescore
  60. 2026-07-04 06:31 UTCEPSS rescore
  61. 2026-07-02 01:22 UTCEG score recompute▲ 6.90
  62. 2026-07-02 01:21 UTCNVD updateCVSS v3 → 6.9 · CVSS v4 → 6.9 · severity → MEDIUM
  63. 2026-06-19 21:23 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55791?
CVE-2026-55791 is a medium vulnerability published on June 19, 2026. Craft CMS is a content management system (CMS). Versions 4.0.0-RC1 and above, prior to 4.18.0 and 5.0.0-RC1, and above, prior to 5.10.0, are vulnerable to Server-Side Request Forgery (SSRF) and Arbitrary JavaScript Injection through the /actions/app/resource-js endpoint. By exploiting the default…
When was CVE-2026-55791 disclosed?
CVE-2026-55791 was first published in the National Vulnerability Database on June 19, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55791 actively exploited?
CVE-2026-55791 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 61.8% of all scored CVEs.
What is the CVSS score of CVE-2026-55791?
CVE-2026-55791 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-55791?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55791, 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.

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