---
cve: "CVE-2026-15806"
severity: "MEDIUM"
cvss: 6.0
epss: "0.4%"
vendor: "Python Software Foundation"
kev: false
exploited: false
published: "2026-08-18 16:17:02"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-25T00:00:46+02:00"
---

# CVE-2026-15806

> 6.0 MEDIUM · 🧪 PoC

## Beschreibung

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-Vektor

```
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- 641be42bb07921ba0f8bffe228b1dc706b092ef6 (Commit)
- 851cf9a7142ecbdd39f831055533f58284ad2bcc (Commit)

## Referenzen

- <https://github.com/python/cpython/issues/155694>
- <https://github.com/python/cpython/pull/155696>
- <https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/>
- <https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8>
- <https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce>
- <https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce>
- <https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6>
- <https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc>
- <http://www.openwall.com/lists/oss-security/2026/08/18/3>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-15806) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_