CVE-2026-39807

MEDIUMNVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
6.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.3Exploit: NoneExposed: 0

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

Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections.

'Elixir.Bandit.Pipeline':determine_scheme/2 in lib/bandit/pipeline.ex returns the client-supplied URI scheme verbatim, ignoring the transport's secure? flag. HTTP/1.1 absolute-form request targets (e.g. GET https://victim/path HTTP/1.1) and the HTTP/2 :scheme pseudo-header are both attacker-controlled strings that flow through this function. Over a plaintext TCP connection, a client can declare https and Bandit will set conn.scheme = :https even though no TLS was negotiated.

Downstream Plug consumers that branch on conn.scheme are silently misled: Plug.SSL's already-secure branch skips its HTTP→HTTPS redirect, cookies emitted with secure: true are sent over plaintext, audit logs record requests as having arrived over HTTPS, and CSRF/SameSite gating may make incorrect decisions.

This issue affects bandit: from 1.0.0 before 1.11.0.

CVSS v3
6.3
EG Score
6.3(medium)
EPSS
36.9%
KEV
Not listed

Published

May 1, 2026

Last Modified

May 5, 2026

Advisory Details (4)

Auto-updated May 1, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-39807
github Patch Available🟡 PoC Available

Bandit trusts client-supplied scheme on plaintext connections · Advisory · mtrudel/bandit · GitHub

https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j
generic

Merge commit from fork · mtrudel/bandit@45feea2 · GitHub

https://github.com/mtrudel/bandit/commit/45feea20dea8af7ffd7245271107b695c040e667
generic

Client-supplied URI scheme trusted without transport verification in bandit | Erlang Ecosystem Foundation CNA

https://cna.erlef.org/cves/CVE-2026-39807.html

Affected Packages

(1 across 1 ecosystem)
Hex(1)
PackageVulnerable rangeFixed inDependents
bandit1.0.0 ... 1.9.0 (41 versions)1.11.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 35× 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.

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

Frequently asked(5)

What is CVE-2026-39807?
CVE-2026-39807 is a medium vulnerability published on May 1, 2026. Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections. 'Elixir.Bandit.Pipeline':determine_scheme/2 in lib/bandit/pipeline.ex returns the client-supplied URI scheme verbatim, ignoring the…
When was CVE-2026-39807 disclosed?
CVE-2026-39807 was first published in the National Vulnerability Database on May 1, 2026, with the most recent update on May 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39807 actively exploited?
CVE-2026-39807 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 36.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39807?
CVE-2026-39807 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-39807?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39807, 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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