CVE-2021-42836 Duplicate Advisory: ReDoS via crafted JSON input in GJSON

High 7.5 Published 22 Oct 2021 Updated 4 Aug 2024

Attackers can cause a denial of service in applications using the GJSON library by triggering a regular expression denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2021-42836?

CVE-2021-42836 is a high-severity denial of service vulnerability in n/a, published on 22 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

GJSON before 1.9.3 allows a ReDoS (regular expression denial of service) attack.

Weakness: CWE-400

Which versions are affected by CVE-2021-42836?

4 open source packages ship an affected version, including github.com/tidwall/gjson. It affects 1 product.

Package	Affected	Fixed in
`github.com/tidwall/gjson` Go	All versions	`1.9.3`
`github.com/tidwall/gjson` Go	All versions	`1.9.3`
`github.com/tidwall/gjson` Go	All versions	`1.9.3`
`github.com/tidwall/gjson` Go	All versions	`1.9.3`

Products include Gjson Project Gjson.

How do I fix CVE-2021-42836?

Upgrade github.com/tidwall/gjson to 1.9.3 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-2021-42836 being exploited?

There is no known exploitation of CVE-2021-42836 in the wild and no public exploit code.

Sources

Also known as CVE-2021-42248, DEBIAN-CVE-2021-42836, GHSA-c9gm-7rfj-8w5h, GHSA-ppj4-34rq-v8j9, UBUNTU-CVE-2021-42836.