CVE-2026-54387

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreHIGH confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-17. the CNA's CVSS baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 3 sources updated this week
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.1Exploit: NoneExposed: 0

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

Tinyproxy through 1.11.3, fixed in commit ff45d3b, fails to reconcile conflicting Content-Length and Transfer-Encoding: chunked headers, forwarding both verbatim to the backend while using Content-Length to determine how many request body bytes to consume. Remote attackers can desynchronize the proxy and backend parser state, allowing injection of arbitrary HTTP requests to the backend to enable cache poisoning, access control bypass, and request hijacking.

CVSS v3
9.1
EG Score
9.1(high)
EPSS
35.2%
KEV
Not listed

Published

June 17, 2026

Last Modified

June 23, 2026

Advisory Details (4)

Auto-updated Jun 17, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

Tinyproxy - HTTP Request Smuggling via CL/TE Desynchronization | Advisories | VulnCheck

https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-cl-te-desynchronization
github_pr

Prevent request smuggling

Fix merged in tinyproxy/tinyproxy PR #610 on 2026-05-07 — awaiting tagged release

https://github.com/tinyproxy/tinyproxy/pull/610
generic

HTTP Request Smuggling: CL/TE desync + duplicate Content-Length forwarding · Issue #609 · tinyproxy/tinyproxy · GitHub

https://github.com/tinyproxy/tinyproxy/issues/609
github_commit

commit ff45d3bf0e61 (tinyproxy/tinyproxy)

Fix landed in tinyproxy/tinyproxy commit ff45d3bf0e61 — awaiting tagged release

https://github.com/tinyproxy/tinyproxy/commit/ff45d3bf0e61d0f8ed97ab379d3047f04eb67521

Vendor Advisories for CVE-2026-54387(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 96× in last 7d / 270× 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 270 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-54387?
CVE-2026-54387 is a critical vulnerability published on June 17, 2026. Tinyproxy through 1.11.3, fixed in commit ff45d3b, fails to reconcile conflicting Content-Length and Transfer-Encoding: chunked headers, forwarding both verbatim to the backend while using Content-Length to determine how many request body bytes to consume. Remote attackers can desynchronize the…
When was CVE-2026-54387 disclosed?
CVE-2026-54387 was first published in the National Vulnerability Database on June 17, 2026, with the most recent update on June 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54387 actively exploited?
CVE-2026-54387 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 35.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-54387?
CVE-2026-54387 has a CVSS v4.0 base score of 9.1 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-54387?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54387, 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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