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: 0.5% (37th percentile of EPSS-scored CVEs). 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: 0.5%CVSS: 6.0Exploit: Elevated riskExposed services: Not assessed

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
6.0MEDIUMmedium confidence
EG Risk
43
EG Risk 43/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
37th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 18, 2026

Last Modified

October 2, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
Patch available. 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(7)

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 / EcosystemFix (by version range) / 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

(12 across 7 ecosystems)
Debian:14(4)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2 ... 8.0.0+dfsg-1 (13 versions)
  • every version on: no fix on record
—
python3.133.13.11-1 ... 3.13.9-1 (9 versions)
  • every version on: no fix on record
—
python3.143.14.0-1 ... 3.14.7-2 (26 versions)
  • every version up to 3.14.7-3: fixed in 3.14.7-3
—
python3.153.15.0~a8-1 ... 3.15.0~rc1-1 (9 versions)
  • every version up to 3.15.0~rc2-1: fixed in 3.15.0~rc2-1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.11+dfsg-2 ... 8.0.0+dfsg-1 (31 versions)
  • every version on: no fix on record
—
python3.113.11.2-6 ... 3.11.9-1 (28 versions)
  • every version on: no fix on record
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2 ... 8.0.0+dfsg-1 (13 versions)
  • every version on: no fix on record
—
python3.133.13.11-1 ... 3.13.9-1 (14 versions)
  • every version on: no fix on record
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.14.8-r0: fixed in 3.14.8-r0
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 36× in last 7d / 109× 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 169 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

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 on August 18, 2026, with the most recent update on October 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 0.5% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-15806?
CVE-2026-15806 has a CVSS base score of 6.0 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-15806?
A fix for CVE-2026-15806 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-15806 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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