CVE-2026-6517

HIGHNVD 7.77.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.7 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.7Exploit: None knownExposed: 0

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

Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651

CVSS v3
7.7
EG Score
7.7(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity77% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
8%
KEV
Not listed

Published

June 15, 2026

Last Modified

June 16, 2026

Advisory Details (1)

Auto-updated Jun 15, 2026
No patch confirmed yet.
generic

Security Updates

https://mattermost.com/security-updates

Vendor Advisories for CVE-2026-6517(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 6× in last 7d / 42× 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 219 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 03:47 UTCEG score recompute
  4. 2026-09-14 03:47 UTCGHSA enrichment
  5. 2026-09-12 15:02 UTCEPSS rescore
  6. 2026-09-11 14:53 UTCEPSS rescore
  7. 2026-09-08 22:01 UTCEPSS rescore
  8. 2026-09-07 16:01 UTCEPSS rescore
  9. 2026-09-06 13:47 UTCEPSS rescore
  10. 2026-09-05 15:31 UTCEPSS rescore
  11. 2026-09-04 05:07 UTCEPSS rescore
  12. 2026-09-02 14:12 UTCEPSS rescore
  13. 2026-09-01 13:54 UTCEPSS rescore
  14. 2026-09-01 04:40 UTCEPSS rescore
  15. 2026-08-30 23:00 UTCEG score recompute
  16. 2026-08-30 23:00 UTCGHSA enrichment
  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. 2026-08-24 23:38 UTCEG score recompute
  23. 2026-08-24 23:38 UTCGHSA enrichment
  24. 2026-08-23 22:28 UTCGHSA enrichment
  25. 2026-08-23 09:49 UTCEG score recompute
Show 75 more
  1. 2026-08-23 09:49 UTCGHSA enrichment
  2. 2026-08-21 23:49 UTCEPSS rescore
  3. 2026-08-21 22:42 UTCGHSA enrichment
  4. 2026-08-21 09:54 UTCEG score recompute
  5. 2026-08-21 09:54 UTCGHSA enrichment
  6. 2026-08-20 22:56 UTCEPSS rescore
  7. 2026-08-20 20:56 UTCGHSA enrichment
  8. 2026-08-20 08:41 UTCEG score recompute
  9. 2026-08-20 08:41 UTCGHSA enrichment
  10. 2026-08-19 17:04 UTCEPSS rescore
  11. 2026-08-19 13:15 UTCEG score recompute
  12. 2026-08-19 13:15 UTCGHSA enrichment
  13. 2026-08-18 13:49 UTCEPSS rescore
  14. 2026-08-18 13:49 UTCEPSS rescore
  15. 2026-08-17 14:29 UTCEG score recompute
  16. 2026-08-17 14:29 UTCGHSA enrichment
  17. 2026-08-17 13:47 UTCEPSS rescore
  18. 2026-08-17 02:08 UTCEG score recompute
  19. 2026-08-17 02:08 UTCGHSA enrichment
  20. 2026-08-16 14:56 UTCEPSS rescore
  21. 2026-08-16 14:56 UTCEPSS rescore
  22. 2026-08-16 13:53 UTCEG score recompute
  23. 2026-08-16 13:53 UTCGHSA enrichment
  24. 2026-08-16 02:15 UTCEPSS rescore
  25. 2026-08-16 01:25 UTCGHSA enrichment
  26. 2026-08-15 13:10 UTCEG score recompute
  27. 2026-08-15 13:10 UTCGHSA enrichment
  28. 2026-08-15 01:31 UTCEPSS rescore
  29. 2026-08-15 00:39 UTCGHSA enrichment
  30. 2026-08-14 12:24 UTCGHSA enrichment
  31. 2026-08-14 00:10 UTCEG score recompute
  32. 2026-08-14 00:10 UTCGHSA enrichment
  33. 2026-08-13 22:00 UTCEPSS rescore
  34. 2026-08-13 11:41 UTCGHSA enrichment
  35. 2026-08-12 23:19 UTCEG score recompute
  36. 2026-08-12 23:19 UTCGHSA enrichment
  37. 2026-08-12 13:51 UTCEPSS rescore
  38. 2026-08-12 11:05 UTCGHSA enrichment
  39. 2026-08-11 22:49 UTCEG score recompute
  40. 2026-08-11 22:49 UTCGHSA enrichment
  41. 2026-08-11 10:27 UTCEG score recompute
  42. 2026-08-11 10:27 UTCGHSA enrichment
  43. 2026-08-11 00:00 UTCEPSS rescore
  44. 2026-08-10 22:13 UTCGHSA enrichment
  45. 2026-08-10 09:58 UTCGHSA enrichment
  46. 2026-08-09 21:44 UTCEG score recompute
  47. 2026-08-09 21:44 UTCGHSA enrichment
  48. 2026-08-09 13:47 UTCEPSS rescore
  49. 2026-08-09 09:29 UTCGHSA enrichment
  50. 2026-08-08 21:15 UTCEG score recompute
  51. 2026-08-08 21:15 UTCGHSA enrichment
  52. 2026-08-08 16:37 UTCEPSS rescore
  53. 2026-08-08 09:00 UTCGHSA enrichment
  54. 2026-08-07 20:46 UTCEG score recompute
  55. 2026-08-07 20:46 UTCGHSA enrichment
  56. 2026-08-07 08:31 UTCGHSA enrichment
  57. 2026-08-06 20:16 UTCEG score recompute
  58. 2026-08-06 20:16 UTCGHSA enrichment
  59. 2026-08-06 13:47 UTCEPSS rescore
  60. 2026-08-06 08:02 UTCGHSA enrichment
  61. 2026-08-05 19:46 UTCEG score recompute
  62. 2026-08-05 19:46 UTCGHSA enrichment
  63. 2026-08-05 19:17 UTCEPSS rescore
  64. 2026-08-05 19:17 UTCEPSS rescore
  65. 2026-08-04 15:43 UTCEG score recompute
  66. 2026-08-04 15:42 UTCGHSA enrichment
  67. 2026-08-04 15:10 UTCEPSS rescore
  68. 2026-08-04 10:39 UTCEPSS rescore
  69. 2026-08-03 22:13 UTCEG score recompute
  70. 2026-08-03 22:13 UTCGHSA enrichment
  71. 2026-08-03 10:36 UTCEPSS rescore
  72. 2026-08-03 09:59 UTCGHSA enrichment
  73. 2026-08-02 21:38 UTCGHSA enrichment
  74. 2026-08-02 09:23 UTCEG score recompute
  75. 2026-08-02 09:23 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-6517?
CVE-2026-6517 is a high vulnerability published on June 15, 2026. Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that…
When was CVE-2026-6517 disclosed?
CVE-2026-6517 was first published in the National Vulnerability Database on June 15, 2026, with the most recent update on June 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6517 actively exploited?
CVE-2026-6517 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 91.5% of all scored CVEs.
What is the CVSS score of CVE-2026-6517?
CVE-2026-6517 has a CVSS v3 base score of 7.7 (NVD).
How do I remediate CVE-2026-6517?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6517, 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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