What is CVE-2018-1061?

CVE-2018-1061 is a medium-severity vulnerability in Python, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2018-06-19.

How severe is CVE-2018-1061?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Improper input validation in Python

CVE-2018-1061

python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2018-06-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.049 (91.8th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 92nd percentile — 91.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.049 · newest: 0.049 · change: 0.000

Affected products

Python — versions 3.7.0
[Unknown] Python — versions python 3.5.6, python 3.4.9, python 3.7.0
Canonical Ubuntu Linux — versions 12.04, 14.04, 16.04
Debian Linux — versions 8.0, 9.0
Fedoraproject Fedora — versions 28, 29, 30
Red Hat Ansible Tower — versions 3.3
Red Hat Enterprise Linux Desktop — versions 7.0
Red Hat Enterprise Linux Server — versions 7.0
Red Hat Enterprise Linux Workstation — versions 7.0

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

www.debian.org/security/2018/dsa-4306 (vendor-advisory, Third Party Advisory)
bugzilla.redhat.com/show_bug.cgi (Issue Tracking)
www.securitytracker.com/id/1042001 (VDB Entry, Third Party Advisory, vdb-entry)
lists.debian.org/debian-lts-announce/2018/09/msg00031.html (mailing-list, Mailing List, Third Party Advisory)
bugs.python.org/issue32981 (Vendor Advisory)
usn.ubuntu.com/3817-2/ (vendor-advisory, Third Party Advisory)
docs.python.org/3.6/whatsnew/changelog.html (Vendor Advisory)
docs.python.org/3.5/whatsnew/changelog.html (Vendor Advisory)
access.redhat.com/errata/RHSA-2018:3505 (vendor-advisory, Third Party Advisory)
access.redhat.com/errata/RHSA-2018:3041 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2018-1061?: CVE-2018-1061 is a medium-severity vulnerability in Python, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2018-06-19.
How severe is CVE-2018-1061?: Medium severity. CVSS v3 base score is 6.5 out of 10.