CVE-2026-15806

MEDIUMPre-NVD 6.06.0—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 65% 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, secondary
Trending — 4 sources updated this weekElevated
6.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.0Exploit: Elevated riskExposed: 0

A fix is available — apply it.

The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://.

Credential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.

Users who cannot upgrade immediately can mitigate by ensuring that applications never make plain http:// requests to hosts for which credentials are registered, for example by not following redirects to http:// URLs.

CVSS v3
6.0
EG Score
6.0(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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
Severity60% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

August 18, 2026

Last Modified

September 2, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic

Mailman 3 [CVE-2026-15806] urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/
github_pr

gh-155694: Scope HTTPPasswordMgr credentials by URL scheme

Fix merged in python/cpython PR #155696 on 2026-08-17 — awaiting tagged release

https://github.com/python/cpython/pull/155696
generic

`HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching · Issue #155694 · python/cpython · GitHub

https://github.com/python/cpython/issues/155694

Vendor Advisories for CVE-2026-15806(3)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpython3-10-main-3.10.21-1.1.hum12026-09-08redhat
redhatpython3-11-main-3.11.16-1.2.hum12026-09-08redhat
redhatpython3-12-main-3.12.14-1.1.hum12026-09-08redhat
redhatpython3-13-main-3.13.15-1.1.hum12026-09-08redhat
redhatpython3-14-main-3.14.7-1.1.hum12026-09-08redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(8 across 3 ecosystems)
Debian:14(4)
PackageVulnerable rangeFixed inDependents
pypy37.3.19+dfsg-2 ... 7.3.23+dfsg-1 (11 versions)——
python3.133.13.11-1 ... 3.13.9-1 (9 versions)——
python3.143.14.0-1 ... 3.14.7-2 (26 versions)——
python3.153.15.0~a8-1 ... 3.15.0~rc1-1 (9 versions)——
Debian:12(2)
PackageVulnerable rangeFixed inDependents
pypy37.3.11+dfsg-2 ... 7.3.23+dfsg-1 (29 versions)——
python3.113.11.2-6 ... 3.11.9-1 (28 versions)——
Debian:13(2)
PackageVulnerable rangeFixed inDependents
pypy37.3.19+dfsg-2 ... 7.3.23+dfsg-1 (11 versions)——
python3.133.13.11-1 ... 3.13.9-1 (13 versions)——

Weakness Classification(2)

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

Additional Vendor Advisories

(4)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 25× in last 7d / 97× 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 108 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-15806?
CVE-2026-15806 is a medium vulnerability published on August 18, 2026. The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used…
When was CVE-2026-15806 disclosed?
CVE-2026-15806 was first published in the National Vulnerability Database on August 18, 2026, with the most recent update on September 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-15806 actively exploited?
CVE-2026-15806 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.3% of all scored CVEs.
What is the CVSS score of CVE-2026-15806?
CVE-2026-15806 has a CVSS v3 base score of 6.0 (NVD).
How do I remediate CVE-2026-15806?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-15806, 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.

Dependency Blast Radius

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