#VU53589 Use-after-free in cURL

Published: 2021-05-26

Vulnerability identifier: #VU53589

Vulnerability risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-22901


Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Client/Desktop applications / Other client software

Vendor: curl.haxx.se


The vulnerability allows a remote attacker to crash the application or compromise the vulnerable system.

The vulnerability exists due to a use-after-free error when processing creation of new TLS sessions or during client certificate negotiation. A remote attacker can force the application to connect to a malicious server, trigger a use-after-free error and crash the application.

Remote code execution is also possible if the application can be forced to initiate multiple transfers with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection in order to inject a crafted memory content into the correct place in memory.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system but requires that libcurl is using OpenSSL.

Install updates from vendor's website.

Vulnerable software versions

cURL: 7.75.0 - 7.76.1

External links

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.

Latest bulletins with this vulnerability