CVE-2026-82639

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-30. the CNA's CVSS baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

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

NextChat versions from 2.15.8 through 2.16.1 contain an improper URL validation vulnerability in the proxy endpoint that allows attackers to obtain the server's OpenAI API key. The x-base-url header is validated using substring matching instead of hostname parsing, allowing any URL containing 'api.openai.com' to pass validation and receive the server's credentials in the Authorization header.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
41%
KEV
Not listed

Published

August 30, 2026

Last Modified

September 24, 2026

Advisory Details (4)

Auto-updated Aug 30, 2026
No patch confirmed yet.
generic

NextChat 2.15.8 through 2.16.1 OpenAI API Key Disclosure | Advisories | VulnCheck

https://www.vulncheck.com/advisories/nextchat-2.15.8-through-2.16.1-openai-api-key-disclosure
generic

NextChat/app/api/proxy.ts at v2.16.1 · ChatGPTNextWeb/NextChat · GitHub

https://github.com/ChatGPTNextWeb/NextChat/blob/v2.16.1/app/api/proxy.ts
generic

GitHub - ChatGPTNextWeb/NextChat: ✨ Light and Fast AI Assistant. Support: Web | iOS | MacOS | Android | Linux | Windows · GitHub

https://github.com/ChatGPTNextWeb/NextChat
generic

Server OpenAI API Key Exfiltration via Incomplete URL Substring Check in Proxy Handler · Issue #6814 · ChatGPTNextWeb/NextChat · GitHub

https://github.com/ChatGPTNextWeb/NextChat/issues/6814

Vendor Advisories for CVE-2026-82639(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 26× in last 7d / 101× 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 101 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-82639?
CVE-2026-82639 is a high vulnerability published on August 30, 2026. NextChat versions from 2.15.8 through 2.16.1 contain an improper URL validation vulnerability in the proxy endpoint that allows attackers to obtain the server's OpenAI API key. The x-base-url header is validated using substring matching instead of hostname parsing, allowing any URL containing…
When was CVE-2026-82639 disclosed?
CVE-2026-82639 was first published in the National Vulnerability Database on August 30, 2026, with the most recent update on September 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-82639 actively exploited?
CVE-2026-82639 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 59.2% of all scored CVEs.
What is the CVSS score of CVE-2026-82639?
CVE-2026-82639 has a CVSS v4.0 base score of 7.5 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-82639?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-82639, 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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