CVE-2026-77776

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-21. A secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.1Exploit: None knownExposed services: Not assessed

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

Headroom's LLM proxy derives the memory owner from the x-headroom-user-id request header. The header is read directly at several points in headroom/proxy/handlers/openai.py, including the chat completion and websocket paths, and nothing binds the value to the caller. A client can therefore name another user's identifier and read or write that user's stored LLM memory. The fix introduces a single resolve_memory_identity seam in headroom/proxy/identity.py that honors the header only for loopback or allowlisted callers and otherwise binds the identity to the proxy-token fingerprint or the operating system user. The pip console script binds 127.0.0.1 by default, but the reference docker-compose.yml ships --host 0.0.0.0 with published ports and no required HEADROOM_PROXY_TOKEN, which the server itself warns about at startup, so a deployment following the shipped compose exposes the affected data-plane routes to the network without authentication.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
56
EG Risk 56/100CISA SSVC

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
Severity91% × 45%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.6%
EPSS %ILE
47th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 21, 2026

Last Modified

September 9, 2026

Advisory Details (5)

Auto-updated Sep 15, 2026
No fix on record yet. Sources: github_pr.
generic

Headroom Proxy Treats the Client-Supplied x-headroom-user-id Header as an Authenticated Identity | Advisories | VulnCheck

https://www.vulncheck.com/advisories/headroom-proxy-treats-the-client-supplied-x-headroom-user-id-header-as-an-authenticated-identity
github_pr

security: address u9up assessment findings (WEB-01–07)

Fix merged in headroomlabs-ai/headroom PR #2207 on 2026-08-20 — awaiting tagged release

https://github.com/headroomlabs-ai/headroom/pull/2207
generic

headroom/headroom/proxy/identity.py at v0.36.1 · headroomlabs-ai/headroom · GitHub

https://github.com/headroomlabs-ai/headroom/blob/v0.36.1/headroom/proxy/identity.py
generic

headroom/headroom/proxy/handlers/openai.py at v0.29.0 · headroomlabs-ai/headroom · GitHub

https://github.com/headroomlabs-ai/headroom/blob/v0.29.0/headroom/proxy/handlers/openai.py
genericMentions a patch (unverified)

GitHub - headroomlabs-ai/headroom: Compress tool outputs, logs, files, and RAG chunks before they reach the LLM. 20% fewer tokens for coding agents, 60-95% fewer tokens for JSON, same answers. Library, proxy, MCP server. · GitHub

https://github.com/headroomlabs-ai/headroom

Vendor Advisories for CVE-2026-77776(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 32× in last 7d / 197× 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 367 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77776?
CVE-2026-77776 is a critical vulnerability published on August 21, 2026. Headroom's LLM proxy derives the memory owner from the x-headroom-user-id request header. The header is read directly at several points in headroom/proxy/handlers/openai.py, including the chat completion and websocket paths, and nothing binds the value to the caller. A client can therefore name…
When was CVE-2026-77776 disclosed?
CVE-2026-77776 was first published on August 21, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77776 actively exploited?
CVE-2026-77776 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (47th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77776?
CVE-2026-77776 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-77776?
No fix for CVE-2026-77776 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-77776 are linked in the Vendor Advisories panel on this page.

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