What’s Vulnerable › Vulnerabilities

CVE-2018-1061

• Severity: high (CVSS 7.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 4.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-06-19 · updated 2026-10-15
• Weakness: CWE-20

Description

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.

Affected products

• Canonical Ubuntu Linux: 12.04, 14.04, 16.04, 18.04
• Debian Linux: 8.0, 9.0
• Fedoraproject Fedora: 28, 29, 30
• Python: before 2.7.15; from 3.0 before 3.4.9; from 3.5.0 through 3.5.5; from 3.6 through 3.6.4; 3.7.0-alpha1, 3.7.0-alpha2, 3.7.0-alpha3, 3.7.0-alpha4, 3.7.0-beta1, 3.7.0-beta2 (+4) — fixed in 2.7.15, 3.4.9
• Tower: 3.3
• RedHat Enterprise Linux Desktop: 7.0
• RedHat Enterprise Linux Server: 7.0
• RedHat Enterprise Linux Workstation: 7.0

How to fix

Upgrade to a fixed version: Python 2.7.15, 3.4.9. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
• http://www.securitytracker.com/id/1042001
• https://access.redhat.com/errata/RHBA-2019:0327
• https://access.redhat.com/errata/RHSA-2018:3041
• https://access.redhat.com/errata/RHSA-2018:3505
• https://access.redhat.com/errata/RHSA-2019:1260
• https://access.redhat.com/errata/RHSA-2019:3725
• https://bugs.python.org/issue32981
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-1061
• https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-6-release-candidate-1
• https://docs.python.org/3.6/whatsnew/changelog.html#python-3-6-5-release-candidate-1
• https://lists.debian.org/debian-lts-announce/2018/09/msg00030.html

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