Improper input validation in Python
CVE-2018-20852
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.039 (89.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 89.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.039 · newest: 0.039 · change: 0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugs.python.org/issue35121 (Exploit, Issue Tracking, Vendor Advisory)
- python-security.readthedocs.io/vuln/cookie-domain-check.html (Vendor Advisory)
- lists.debian.org/debian-lts-announce/2019/08/msg00022.html (mailing-list)
- lists.opensuse.org/opensuse-security-announce/2019-08/msg00071.html (vendor-advisory)
- lists.opensuse.org/opensuse-security-announce/2019-08/msg00074.html (vendor-advisory)
- lists.debian.org/debian-lts-announce/2019/08/msg00040.html (mailing-list)
- usn.ubuntu.com/4127-2/ (vendor-advisory)
- usn.ubuntu.com/4127-1/ (vendor-advisory)
- access.redhat.com/errata/RHSA-2019:3725 (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2018-20852?
- CVE-2018-20852 is a medium-severity vulnerability in Python, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2019-07-13.
- How severe is CVE-2018-20852?
- Medium severity. CVSS v3 base score is 5.3 out of 10.
- Is CVE-2018-20852 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.