CVE-2026-54387

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-17. 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
9.1
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(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
35.8%
KEV
Not listed

Published

June 17, 2026

Last Modified

July 14, 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 12× in last 7d / 188× 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 235 total refreshes for this CVE.

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

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 July 14, 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 35.8% 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 v3 base score of 9.1 (NVD).
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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