#VU53004 Use-after-free in Ruby on Rails - CVE-2021-22904

Vulnerability identifier: #VU53004

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-22904

CWE-ID: CWE-416

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Ruby on Rails
Universal components / Libraries / Scripting languages

Vendor: Rails

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a use-after-free error in the Token Authentication logic in Action Controller. A remote attacker can send a specially crafted request and cause a denial of service condition on the target system. 

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Ruby on Rails: 4.0.0 rc1 - 4.0.13, 4.1.0 rc1 - 4.1.16, 4.2.0 rc1 - 4.2.11.3, 5.0.0.racecar1 - 5.0.7.2, 5.1.0 rc1 - 5.1.7, 5.2.0 - 5.2.5, 6.0.0 - 6.0.3.6, 6.1.0 - 6.1.3.1

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External links
https://seclists.org/oss-sec/2021/q2/102

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.