# CVE-2018-1061: Python 3.5 and 2 others: python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking…

CVE-2018-1061 is fixed in 2 products on 1 platform, first by Python 3.6 3.6.5, released March 28, 2018. 1 other affected product has no fix yet. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2018-1061
- Priority: High
- CVSS: 7.5
- EPSS: 0.0474
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 19, 2018
- Weakness: CWE-20
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2018-1061

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Python 3.6 | 3.6.5 | [Python 3.6 3.6.5](https://patchblox.com/security/data/fix/windows-app/python.python.3.6-3.6.5.md) | Mar 28, 2018 |
| Windows apps | Python 3.7 | 3.7.1 | [Python 3.7 3.7.1](https://patchblox.com/security/data/fix/windows-app/python.python.3.7-3.7.1.md) | Oct 20, 2018 |

## No fix yet

| Platform | Product | Status |
|---|---|---|
| Windows apps | Python 3.5 | no-fix |

---

Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.