No exploitation reportedFix available

CVE-2018-1061

Q: Is CVE-2018-1061 actively exploited?

Active exploitation of CVE-2018-1061 has not been confirmed. Its EPSS score was 4.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2018-1061?

CVE-2018-1061 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2018-06-19
Fixed in3.4.9 · 2.7.15
WeaknessCWE-20

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2018-06-1912:29CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2018-1061?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2018-1061?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Python

Branch	Affected	Fixed in	Source
3.x	≥ 3.0, < 3.4.9	3.4.9	NVD
2.7	< 2.7.15	2.7.15	NVD
3.5	≥ 3.5.0, ≤ 3.5.5	no fix published	NVD
3.6	≥ 3.6, ≤ 3.6.4	no fix published	NVD
3.7	= 3.7.0	no fix published	NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
12.4	= 12.04	no fix published	NVD
14.4	= 14.04	no fix published	NVD
16.4	= 16.04	no fix published	NVD
18.4	= 18.04	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
28.x	= 28	no fix published	NVD
29.x	= 29	no fix published	NVD
30.x	= 30	no fix published	NVD

5 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Python to 3.4.9 · 2.7.15

Advisories and patches

bugs.python.orgVendor Advisory
docs.python.orgVendor Advisory
docs.python.orgVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CISA-ADPSSVC decisionnone2026-10-15
OpenCVESSVC decisionnone—
CNACVSS 3.06.5read 2026-10-23
NVDCVSS 3.07.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
CNAweakness (CWE)CWE-20read 2026-10-23
FIRST EPSSEPSS score4.9 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2018-06-19
Last Modified: 2026-10-15
NVD status: Modified

Frequently asked questions

What is CVE-2018-1061?

Is CVE-2018-1061 actively exploited?

Active exploitation of CVE-2018-1061 has not been confirmed. Its EPSS score was 4.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-1061?

CVE-2018-1061 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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