`HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching (CVE-2026-15806)
Published Last modified Sources: SUSE, BSI, Red Hat, Debian LTS, OSV, CVE.org, Msrc Update Guide
What is affected, what to do
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.
Update Python Software Foundation CPython to version 3.10.22, Python Software Foundation CPython to version 3.11.17, Python Software Foundation CPython to version 3.12.15.
- Affected
- Python Software Foundation CPython
lt *..3.10.22 - Python Software Foundation CPython
lt 3.11.0..3.11.17 - Python Software Foundation CPython
lt 3.12.0..3.12.15 - Python Software Foundation CPython
lt 3.13.0..3.13.16 - Python Software Foundation CPython
lt 3.14.0..3.14.8 - Python Software Foundation CPython
lt 3.15.0a1..3.15.0rc2
- Python Software Foundation CPython
- Fixed in
- Python Software Foundation CPython
3.10.22 - Python Software Foundation CPython
3.11.17 - Python Software Foundation CPython
3.12.15 - Python Software Foundation CPython
3.13.16 - Python Software Foundation CPython
3.14.8 - Python Software Foundation CPython
3.15.0rc2
- Python Software Foundation CPython
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Metrics
6.0
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v4
6.0
CVSS v4
Severity Medium on the scale from 0 to 10.
Source: SUSE, BSI, Red Hat, Debian LTS, OSV, CVE.org, Msrc Update Guide
0.5 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 44.5
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 69.63 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 6.0 Methodology
CVSS v4
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 6.0
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.5 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 44.5
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-319, CWE-522
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
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.
Source: suse_csaf, BSI WID Portal, BSI CSAF, redhat_csaf, Debian LTS Advisories, OSV (Open Source Vulnerabilities), NVD (NIST), cvelistv5, Microsoft Security Update Guide
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Python Software Foundation | CPython |
|
|
| Open Source | Python |
|
|
Distribution and container packages (4)
Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.
| Affected versions | Fixed in | ||
|---|---|---|---|
| bitnami | python-min |
|
|
Vendors and products
Affected operating systems
| Linux | debian | python3.11 | bookworm |
Weakness classes (CWE)
CWE-319Cleartext Transmission of Sensitive Information
Base
The product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.
Entry at MITRE CWE-319CWE-522Insufficiently Protected Credentials
Class
The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.
Entry at MITRE CWE-522
References & sources
- github.compython/cpython/issues/155694Issue tracking
- github.compython/cpython/pull/155696Patch
- mail.python.orgarchives/list/security-announce@python.org/thread/3OKPE5S75KDNA…Vendor advisory
- github.compython/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8Patch
- github.compython/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348cePatch
- github.compython/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837cePatch
- openwall.comlists/oss-security/2026/08/18/3
- github.compython/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6Patch
- github.compython/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bccPatch
- NVD (NIST)vuln/detail/CVE-2026-15806web
- github.compython/cpython/commit/95355ee3a8e1d3c3d4858d1973aa42a9b91a2801fix, Patch
- github.compython/cpython/commit/dac88d8615078c55f1304ea4c7a2d822700d4e5afix, Patch
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedpython.org
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/15xxx/CVE-2026-15806.json">CVE-2026-15806</a>Source identifier: cna@python.org
Record modifiedpython.org
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/commit/95355ee3a8e1d3c3d4858d1973aa42a9b91a2801Reference added —https://github.com/python/cpython/commit/dac88d8615078c55f1304ea4c7a2d822700d4e5aSource identifier: cna@python.org
Record modifiedpython.org
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/15xxx/CVE-2026-15806.json">CVE-2026-15806</a>Source identifier: cna@python.org
Record modifiedpython.org
New references:- https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6
- https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc
- https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8
- https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce
and 4 more references
Show 17 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/15xxx/CVE-2026-15806.json">CVE-2026-15806</a>Reference added —https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6Reference added —https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bccReference added —https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8Reference added —https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ceReference added —https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ceReference added —https://github.com/python/cpython/issues/155694Reference added —https://github.com/python/cpython/pull/155696Reference added —https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/Reference removed https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6—Reference removed https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc—Reference removed https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8—Reference removed https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce—Reference removed https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce—Reference removed https://github.com/python/cpython/issues/155694—Reference removed https://github.com/python/cpython/pull/155696—Reference removed https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/—Source identifier: cna@python.org
Record modifiedCISA ADP
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/issues/155694Reference removed https://github.com/python/cpython/issues/155694—Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Show 3 older changes
Record modifiedCVE Program
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://www.openwall.com/lists/oss-security/2026/08/18/3Reference removed http://www.openwall.com/lists/oss-security/2026/08/18/3—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedpython.org
Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bccSource identifier: cna@python.org
Record modifiedpython.org
Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6Source identifier: cna@python.org
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-15806"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-15806.svg?lang=en" alt="CVE-2026-15806 – NEOSEC Intel" height="20"></a>