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 91% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
7.7
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.7Exploit: NoneExposed: 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
8.5%
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 14× in last 7d / 66× 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. 2026-07-25 14:18 UTCEPSS rescore
  2. 2026-07-25 14:18 UTCEPSS rescore
  3. 2026-07-24 14:18 UTCEPSS rescore
  4. 2026-07-24 14:18 UTCEPSS rescore
  5. 2026-07-23 14:18 UTCEPSS rescore
  6. 2026-07-23 14:18 UTCEPSS rescore
  7. 2026-07-23 03:22 UTCEG score recompute▲ 1.40
  8. 2026-07-22 14:08 UTCEPSS rescore
  9. 2026-07-22 14:08 UTCEPSS rescore
  10. 2026-07-21 15:25 UTCEPSS rescore
  11. 2026-07-21 15:25 UTCEPSS rescore
  12. 2026-07-20 17:08 UTCEPSS rescore
  13. 2026-07-19 14:31 UTCEPSS rescore
  14. 2026-07-19 02:29 UTCEPSS rescore
  15. 2026-07-18 10:04 UTCEPSS rescore
  16. 2026-07-17 06:37 UTCGHSA enrichment
  17. 2026-07-16 17:03 UTCEPSS rescore
  18. 2026-07-16 08:35 UTCGHSA enrichment
  19. 2026-07-15 16:57 UTCEPSS rescore
  20. 2026-07-15 10:01 UTCGHSA enrichment
  21. 2026-07-15 02:00 UTCEPSS rescore
  22. 2026-07-15 02:00 UTCEPSS rescore
  23. 2026-07-14 11:52 UTCGHSA enrichment
  24. 2026-07-13 22:31 UTCEPSS rescore
  25. 2026-07-13 13:49 UTCGHSA enrichment
Show 70 more
  1. 2026-07-13 06:13 UTCEPSS rescore
  2. 2026-07-13 06:13 UTCEPSS rescore
  3. 2026-07-12 15:49 UTCGHSA enrichment
  4. 2026-07-12 05:46 UTCEPSS rescore
  5. 2026-07-11 17:17 UTCGHSA enrichment
  6. 2026-07-10 19:11 UTCGHSA enrichment
  7. 2026-07-09 21:11 UTCGHSA enrichment
  8. 2026-07-09 19:10 UTCEPSS rescore
  9. 2026-07-09 19:10 UTCEPSS rescore
  10. 2026-07-08 20:30 UTCGHSA enrichment
  11. 2026-07-08 15:16 UTCEPSS rescore
  12. 2026-07-08 15:16 UTCEPSS rescore
  13. 2026-07-07 22:24 UTCGHSA enrichment
  14. 2026-07-07 13:46 UTCEPSS rescore
  15. 2026-07-07 13:46 UTCEPSS rescore
  16. 2026-07-07 00:24 UTCGHSA enrichment
  17. 2026-07-06 16:27 UTCEPSS rescore
  18. 2026-07-06 16:27 UTCEPSS rescore
  19. 2026-07-06 02:23 UTCEPSS rescore
  20. 2026-07-06 02:23 UTCEPSS rescore
  21. 2026-07-05 21:24 UTCGHSA enrichment
  22. 2026-07-05 02:31 UTCEPSS rescore
  23. 2026-07-05 02:30 UTCEPSS rescore
  24. 2026-07-04 23:00 UTCGHSA enrichment
  25. 2026-07-04 06:31 UTCEPSS rescore
  26. 2026-07-04 06:31 UTCEPSS rescore
  27. 2026-07-04 01:00 UTCGHSA enrichment
  28. 2026-07-03 02:32 UTCGHSA enrichment
  29. 2026-07-02 04:32 UTCGHSA enrichment
  30. 2026-07-01 15:07 UTCEPSS rescore
  31. 2026-07-01 06:31 UTCGHSA enrichment
  32. 2026-06-30 08:31 UTCGHSA enrichment
  33. 2026-06-29 14:06 UTCEPSS rescore
  34. 2026-06-29 10:29 UTCGHSA enrichment
  35. 2026-06-28 14:07 UTCEPSS rescore
  36. 2026-06-28 12:29 UTCGHSA enrichment
  37. 2026-06-28 04:56 UTCEPSS rescore
  38. 2026-06-27 14:30 UTCGHSA enrichment
  39. 2026-06-27 03:08 UTCEPSS rescore
  40. 2026-06-26 16:28 UTCGHSA enrichment
  41. 2026-06-25 18:29 UTCGHSA enrichment
  42. 2026-06-25 13:50 UTCEPSS rescore
  43. 2026-06-24 20:27 UTCGHSA enrichment
  44. 2026-06-24 14:05 UTCEPSS rescore
  45. 2026-06-23 22:17 UTCGHSA enrichment
  46. 2026-06-23 21:33 UTCEPSS rescore
  47. 2026-06-23 21:33 UTCEPSS rescore
  48. 2026-06-22 23:44 UTCGHSA enrichment
  49. 2026-06-22 14:25 UTCEPSS rescore
  50. 2026-06-22 14:25 UTCEPSS rescore
  51. 2026-06-22 01:43 UTCGHSA enrichment
  52. 2026-06-21 14:56 UTCEPSS rescore
  53. 2026-06-21 14:56 UTCEPSS rescore
  54. 2026-06-21 02:24 UTCGHSA enrichment
  55. 2026-06-21 01:59 UTCEPSS rescore
  56. 2026-06-21 01:59 UTCEPSS rescore
  57. 2026-06-20 04:22 UTCGHSA enrichment
  58. 2026-06-19 19:26 UTCEPSS rescore
  59. 2026-06-19 19:26 UTCEPSS rescore
  60. 2026-06-19 06:14 UTCGHSA enrichment
  61. 2026-06-18 17:52 UTCEPSS rescore
  62. 2026-06-18 17:52 UTCEPSS rescore
  63. 2026-06-18 08:11 UTCGHSA enrichment
  64. 2026-06-17 17:53 UTCEPSS rescore
  65. 2026-06-17 10:07 UTCGHSA enrichment
  66. 2026-06-16 17:53 UTCEPSS rescore
  67. 2026-06-16 17:47 UTCNVD updateCVSS v3 → 7.7 · severity → HIGH
  68. 2026-06-16 12:07 UTCGHSA enrichment
  69. 2026-06-15 14:06 UTCEG score recompute
  70. 2026-06-15 14:03 UTCMITRE cvelistV5first tracked

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 8.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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

Explore the affected products and dependency analysis for CVE-2026-6517

Explore →

Is Your Infrastructure Affected by CVE-2026-6517?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs