CVE-2026-54388

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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: the CNA's CVSS, EPSS, GitHub Security Advisory
Elevated

Also known asEUVD-2026-37790 (ENISA EUVD) · GHSA-p3h9-73g9-x6m3 (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan mitigationThe upstream fix is not in a release yet: until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 9.1Exploit: No code on recordExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while using the first value 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
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.
EPSS PROB
0.4%
EPSS %ILE
38th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 17, 2026

Last Modified

November 8, 2026

Advisory Details (4)

Auto-updated Sep 16, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
Web page

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

https://github.com/tinyproxy/tinyproxy/issues/609
Web page

Tinyproxy - HTTP Request Smuggling via Duplicate Content-Length Headers | Advisories | VulnCheck

https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplicate-content-length-headers
GitHub pull request

Prevent request smuggling

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

https://github.com/tinyproxy/tinyproxy/pull/610
GitHub commit

commit 364cdb67e0ea (tinyproxy/tinyproxy)

Fix landed in tinyproxy/tinyproxy commit 364cdb67e0ea — awaiting tagged release

https://github.com/tinyproxy/tinyproxy/commit/364cdb67e0ea00a8e4a7037e2693e0711e816adb

Vendor Advisories for CVE-2026-54388(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 2 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
tinyproxy1.10.0-5 ... 1.11.3-1~bpo13+1 (15 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
tinyproxy1.11.2-1, 1.11.3-1, 1.11.3-1~bpo13+1
  • every version on: no fix on record
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 59× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 570 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 470 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  2. 2026-11-12 18:16 UTCEchelonGraph re-scored
  3. 2026-11-12 18:16 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  4. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  5. 2026-11-11 17:16 UTCEchelonGraph re-scored
  6. 2026-11-11 17:16 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  7. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  8. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  9. 2026-11-10 16:17 UTCEchelonGraph re-scored
  10. 2026-11-10 16:17 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  11. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  12. 2026-11-09 15:14 UTCEchelonGraph re-scored
  13. 2026-11-09 15:14 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  14. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  15. 2026-11-08 14:16 UTCEchelonGraph re-scored
  16. 2026-11-08 14:16 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  17. 2026-11-08 09:10 UTCEchelonGraph re-scored
  18. 2026-11-08 09:10 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  20. 2026-11-07 08:11 UTCEchelonGraph re-scored
  21. 2026-11-07 08:11 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  22. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  23. 2026-11-06 11:55 UTCOSV refresh
  24. 2026-11-06 07:12 UTCEchelonGraph re-scored
  25. 2026-11-06 07:12 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
Show 75 more
  1. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  2. 2026-11-05 06:12 UTCEchelonGraph re-scored
  3. 2026-11-05 06:12 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  4. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  5. 2026-11-04 05:13 UTCEchelonGraph re-scored
  6. 2026-11-04 05:13 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  7. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  8. 2026-11-03 04:13 UTCEchelonGraph re-scored
  9. 2026-11-03 04:13 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  10. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  11. 2026-11-02 03:07 UTCEchelonGraph re-scored
  12. 2026-11-02 03:07 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  13. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  14. 2026-11-01 02:08 UTCEchelonGraph re-scored
  15. 2026-11-01 02:08 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  16. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  17. 2026-10-31 01:09 UTCEchelonGraph re-scored
  18. 2026-10-31 01:09 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  20. 2026-10-30 00:10 UTCEchelonGraph re-scored
  21. 2026-10-30 00:10 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  22. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  23. 2026-10-28 23:11 UTCEchelonGraph re-scored
  24. 2026-10-28 23:11 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  25. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  26. 2026-10-27 22:12 UTCEchelonGraph re-scored
  27. 2026-10-27 22:11 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  28. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  29. 2026-10-26 21:08 UTCEchelonGraph re-scored
  30. 2026-10-26 21:07 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  31. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  32. 2026-10-25 18:04 UTCEchelonGraph re-scored
  33. 2026-10-25 18:04 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  34. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  35. 2026-10-25 14:19 UTCEchelonGraph re-scored
  36. 2026-10-24 16:35 UTCEchelonGraph re-scored
  37. 2026-10-24 16:35 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  38. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  39. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  40. 2026-10-23 15:35 UTCEchelonGraph re-scored
  41. 2026-10-23 15:35 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  42. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  43. 2026-10-22 14:34 UTCEchelonGraph re-scored
  44. 2026-10-22 14:34 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  45. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  46. 2026-10-21 13:34 UTCEchelonGraph re-scored
  47. 2026-10-21 13:34 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  48. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  49. 2026-10-20 12:36 UTCEchelonGraph re-scored
  50. 2026-10-20 12:35 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  51. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  52. 2026-10-19 11:35 UTCEchelonGraph re-scored
  53. 2026-10-19 11:35 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  54. 2026-10-18 09:22 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  55. 2026-10-18 03:31 UTCEchelonGraph re-scored
  56. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  57. 2026-10-17 08:22 UTCEchelonGraph re-scored
  58. 2026-10-17 08:22 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  59. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  60. 2026-10-16 07:22 UTCEchelonGraph re-scored
  61. 2026-10-16 07:22 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  62. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  63. 2026-10-15 06:18 UTCEchelonGraph re-scored
  64. 2026-10-15 06:18 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  65. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  66. 2026-10-14 01:58 UTCEchelonGraph re-scored
  67. 2026-10-14 01:58 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  68. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  69. 2026-10-12 22:15 UTCEchelonGraph re-scored
  70. 2026-10-12 22:14 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  71. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  72. 2026-10-12 15:56 UTCEchelonGraph re-scored
  73. 2026-10-12 06:56 UTCGHSA enrichmentGHSA-p3h9-73g9-x6m3 · GitHub severity CRITICAL · GitHub CVSS 9.1
  74. 2026-10-11 19:39 UTCEchelonGraph re-scored
  75. 2026-10-11 16:54 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2026-54388?
CVE-2026-54388 is a critical-severity vulnerability; its CVE record was published on June 17, 2026. Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while using the first value to determine how many request body bytes to consume. Remote attackers can…
When was CVE-2026-54388 made public?
CVE-2026-54388 was made public on May 7, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on June 17, 2026. EchelonGraph's copy of the record carries a last-modified date of November 8, 2026; the record at its source may have been updated since.
Is CVE-2026-54388 actively exploited?
CVE-2026-54388 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (38th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-54388?
CVE-2026-54388 has a CVSS base score of 9.1 (the CNA's own assessment, by vulncheck; NVD's own analysis pending).
How do I remediate CVE-2026-54388?
An upstream fix for CVE-2026-54388 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-54388 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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