CVE-2026-4858

HIGHNVD 8.08.0—
EchelonGraph scoreMEDIUM confidence

Score 8.0 from GitHub Security Advisory (severity: HIGH) published 2026-05-21. NVD baseline CVSS 8.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.0Exploit: NoneExposed: 0

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

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640

CVSS v3
8.0
EG Score
8.0(medium)
EPSS
16.1%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 21, 2026

Advisory Details (1)

Auto-updated Jun 4, 2026
No patch confirmed yet.
generic

Security Updates

https://mattermost.com/security-updates

Vendor Advisories for CVE-2026-4858(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)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/mattermost/mattermost-server11.6.011.6.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 68× 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.

Showing the most recent 100 of 146 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-11 08:27 UTCEPSS rescore
  3. 2026-07-09 19:10 UTCEPSS rescore
  4. 2026-07-09 19:10 UTCEPSS rescore
  5. 2026-07-08 15:16 UTCEPSS rescore
  6. 2026-07-07 13:46 UTCEPSS rescore
  7. 2026-07-06 16:27 UTCEPSS rescore
  8. 2026-07-06 02:23 UTCEPSS rescore
  9. 2026-07-05 02:30 UTCEPSS rescore
  10. 2026-07-01 15:07 UTCEPSS rescore
  11. 2026-06-30 23:22 UTCEPSS rescore
  12. 2026-06-29 20:13 UTCEG score recompute
  13. 2026-06-29 14:06 UTCEPSS rescore
  14. 2026-06-29 14:06 UTCEPSS rescore
  15. 2026-06-28 14:07 UTCEPSS rescore
  16. 2026-06-28 07:54 UTCEG score recompute
  17. 2026-06-28 04:56 UTCEPSS rescore
  18. 2026-06-28 04:56 UTCEPSS rescore
  19. 2026-06-27 19:59 UTCEG score recompute
  20. 2026-06-27 07:23 UTCEG score recompute
  21. 2026-06-27 03:08 UTCEPSS rescore
  22. 2026-06-26 19:26 UTCEG score recompute
  23. 2026-06-26 03:40 UTCEG score recompute
  24. 2026-06-25 14:29 UTCEG score recompute
  25. 2026-06-25 13:49 UTCEPSS rescore
Show 75 more
  1. 2026-06-24 14:05 UTCEPSS rescore
  2. 2026-06-23 21:33 UTCEPSS rescore
  3. 2026-06-23 21:33 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-22 14:25 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 14:56 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-21 01:59 UTCEPSS rescore
  10. 2026-06-19 19:26 UTCEPSS rescore
  11. 2026-06-19 19:26 UTCEPSS rescore
  12. 2026-06-18 17:52 UTCEPSS rescore
  13. 2026-06-18 17:52 UTCEPSS rescore
  14. 2026-06-17 23:12 UTCEG score recompute
  15. 2026-06-17 23:12 UTCGHSA enrichment
  16. 2026-06-17 17:53 UTCEPSS rescore
  17. 2026-06-17 11:15 UTCEG score recompute
  18. 2026-06-17 11:15 UTCGHSA enrichment
  19. 2026-06-16 20:02 UTCEG score recompute
  20. 2026-06-16 20:02 UTCGHSA enrichment
  21. 2026-06-16 17:53 UTCEPSS rescore
  22. 2026-06-16 03:40 UTCEG score recompute
  23. 2026-06-16 03:40 UTCGHSA enrichment
  24. 2026-06-15 17:49 UTCEPSS rescore
  25. 2026-06-15 17:49 UTCEPSS rescore
  26. 2026-06-15 15:44 UTCEG score recompute
  27. 2026-06-15 15:44 UTCGHSA enrichment
  28. 2026-06-15 02:02 UTCEG score recompute
  29. 2026-06-15 02:02 UTCGHSA enrichment
  30. 2026-06-14 23:18 UTCEPSS rescore
  31. 2026-06-14 14:07 UTCEG score recompute
  32. 2026-06-14 14:07 UTCGHSA enrichment
  33. 2026-06-14 02:04 UTCEG score recompute
  34. 2026-06-14 02:04 UTCGHSA enrichment
  35. 2026-06-13 23:00 UTCEPSS rescore
  36. 2026-06-13 14:08 UTCEG score recompute
  37. 2026-06-13 14:08 UTCGHSA enrichment
  38. 2026-06-13 01:05 UTCEG score recompute
  39. 2026-06-13 01:05 UTCGHSA enrichment
  40. 2026-06-12 23:12 UTCEPSS rescore
  41. 2026-06-12 23:12 UTCEPSS rescore
  42. 2026-06-12 13:09 UTCEG score recompute
  43. 2026-06-12 13:09 UTCGHSA enrichment
  44. 2026-06-12 01:12 UTCEG score recompute
  45. 2026-06-12 01:12 UTCGHSA enrichment
  46. 2026-06-11 14:00 UTCEPSS rescore
  47. 2026-06-11 13:16 UTCEG score recompute
  48. 2026-06-11 13:16 UTCGHSA enrichment
  49. 2026-06-11 01:20 UTCEG score recompute
  50. 2026-06-11 01:20 UTCGHSA enrichment
  51. 2026-06-10 22:19 UTCEPSS rescore
  52. 2026-06-10 13:25 UTCEG score recompute
  53. 2026-06-10 13:25 UTCGHSA enrichment
  54. 2026-06-10 13:22 UTCEPSS rescore
  55. 2026-06-10 01:29 UTCEG score recompute
  56. 2026-06-10 01:29 UTCGHSA enrichment
  57. 2026-06-09 13:34 UTCEG score recompute
  58. 2026-06-09 13:33 UTCGHSA enrichment
  59. 2026-06-09 01:38 UTCEG score recompute
  60. 2026-06-09 01:38 UTCGHSA enrichment
  61. 2026-06-08 14:17 UTCEPSS rescore
  62. 2026-06-08 14:17 UTCEPSS rescore
  63. 2026-06-08 13:39 UTCEG score recompute
  64. 2026-06-08 13:39 UTCGHSA enrichment
  65. 2026-06-08 01:44 UTCEG score recompute
  66. 2026-06-08 01:44 UTCGHSA enrichment
  67. 2026-06-07 15:25 UTCEPSS rescore
  68. 2026-06-07 15:25 UTCEPSS rescore
  69. 2026-06-07 13:49 UTCEG score recompute
  70. 2026-06-07 13:49 UTCGHSA enrichment
  71. 2026-06-07 01:54 UTCEG score recompute
  72. 2026-06-07 01:54 UTCGHSA enrichment
  73. 2026-06-06 13:58 UTCEG score recompute
  74. 2026-06-06 13:58 UTCGHSA enrichment
  75. 2026-06-06 13:47 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-4858?
CVE-2026-4858 is a high vulnerability published on May 21, 2026. Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action…
When was CVE-2026-4858 disclosed?
CVE-2026-4858 was first published in the National Vulnerability Database on May 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-4858 actively exploited?
CVE-2026-4858 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 16.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-4858?
CVE-2026-4858 has a CVSS v3 base score of 8.0 (NVD).
How do I remediate CVE-2026-4858?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4858, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-4858

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