CVE-2020-28493 Regular Expression Denial of Service (ReDoS)

What is CVE-2020-28493?

CVE-2020-28493 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 1 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

This affects the package jinja2 from 0.0.0 and before 2.11.3. The ReDoS vulnerability is mainly due to the `_punctuation_re regex` operator and its use of multiple wildcards. The last wildcard is the most exploitable as it searches for trailing punctuation. This issue can be mitigated by Markdown to format user content instead of the urlize filter, or by implementing request timeouts and limiting process memory.

Weakness: CWE-400

Which versions are affected by CVE-2020-28493?

3 open source packages ship an affected version, including jinja2 and Jinja2. It affects 2 products.

Products include Fedoraproject Fedora, Palletsprojects Jinja.

How do I fix CVE-2020-28493?

Upgrade jinja2 to 2.11.3 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-28493 being exploited?

There is no known exploitation of CVE-2020-28493 in the wild and no public exploit code.

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• CVE-2024-4947 Google Chromium V8 Type Confusion Exploited Critical 9.6
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All Fedoraproject Fedora vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2020-28493, ALSA-2021:4161, AZL-40857, AZL-75813, DEBIAN-CVE-2020-28493, GHSA-g3rq-g295-4j3m and 14 more.