CVE-2018-20852http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong serv…
Updated under an hour ago ()
Does this affect you?
It affects python. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.
- CVSS
- 4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-20
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Oct 7, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
python python python:python | from 2.0 through 2.7.16; from 3.0.0 before 3.4.10; from 3.5.0 before 3.5.7; from 3.6.0 before 3.6.9; from 3.7.0 before 3.7.3 | NVD |
References
- http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00071.html
- http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00074.html
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- https://access.redhat.com/errata/RHSA-2019:3725
- https://access.redhat.com/errata/RHSA-2019:3948
- https://bugs.python.org/issue35121exploit, issue-tracking, vendor-advisory
- https://lists.debian.org/debian-lts-announce/2019/08/msg00022.html
- https://lists.debian.org/debian-lts-announce/2019/08/msg00040.html
- https://lists.debian.org/debian-lts-announce/2020/07/msg00011.html
- https://lists.debian.org/debian-lts-announce/2020/08/msg00034.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/COATURTCY7G67AYI6UDV5B2JZTBCKIDX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K7HNVIFMETMFWWWUNTB72KYJYXCZOS5V/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZBTGPBUABGXZ7WH7677OEM3NSP6ZEA76/
- https://python-security.readthedocs.io/vuln/cookie-domain-check.htmlvendor-advisory
- https://security.gentoo.org/glsa/202003-26
- https://usn.ubuntu.com/4127-1/
- https://usn.ubuntu.com/4127-2/
- https://www.oracle.com/security-alerts/cpuapr2020.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.