CVE-2026-6957

HIGHNVD 4.98.0▲
EchelonGraph scoreMEDIUM confidence

Score 8.0 from GitHub Security Advisory (severity: HIGH) published 2026-05-27. NVD baseline CVSS 4.9; sources differ by 3.1.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
8.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.9Exploit: None knownExposed: 0

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

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

CVSS v3
4.9
EG Score
8.0(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
Severity80% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

May 27, 2026

Last Modified

June 2, 2026

Advisory Details (1)

Auto-updated Jun 3, 2026
No patch confirmed yet.
generic

Security Updates

https://mattermost.com/security-updates

Vendor Advisories for CVE-2026-6957(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 38× 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 234 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-6957?
CVE-2026-6957 is a high vulnerability published on May 27, 2026. Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via…
When was CVE-2026-6957 disclosed?
CVE-2026-6957 was first published in the National Vulnerability Database on May 27, 2026, with the most recent update on June 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6957 actively exploited?
CVE-2026-6957 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 77.8% of all scored CVEs.
What is the CVSS score of CVE-2026-6957?
CVE-2026-6957 has a CVSS v3 base score of 4.9 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.0.
How do I remediate CVE-2026-6957?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6957, 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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