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Django Denial-of-service possibility in truncatechars_html and truncatewords_html template filters

Moderate severity GitHub Reviewed Published Jan 4, 2019 to the GitHub Advisory Database • Updated Mar 7, 2024

Package

pip django (pip)

Affected versions

>= 2.0, < 2.0.3
>= 1.11, < 1.11.11
>= 1.8, < 1.8.19

Patched versions

2.0.3
1.11.11
1.8.19

Description

An issue was discovered in Django 2.0 before 2.0.3, 1.11 before 1.11.11, and 1.8 before 1.8.19. If django.utils.text.Truncator's chars() and words() methods were passed the html=True argument, they were extremely slow to evaluate certain inputs due to a catastrophic backtracking vulnerability in a regular expression. The chars() and words() methods are used to implement the truncatechars_html and truncatewords_html template filters, which were thus vulnerable.

References

Published to the GitHub Advisory Database Jan 4, 2019
Reviewed Jun 16, 2020
Last updated Mar 7, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

0.955%
(84th percentile)

Weaknesses

CVE ID

CVE-2018-7537

GHSA ID

GHSA-2f9x-5v75-3qv4

Source code

Credits

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