CVE-2021-22926: haxx curl Business Logic Errors

Vulnerability summary

CVE-2021-22926 is a high (CVSS 7.5) Business Logic Errors vulnerability in haxx curl. EPSS estimates a 15.14% chance of exploitation in the next 30 days, higher than 96.7% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 05-08-2021
   PublishedVulnerability first disclosed.
2. 14-10-2026
   Last modifiedVulnerability information updated.

Description

libcurl-using applications can ask for a specific client certificate to be used in a transfer. This is done with the `CURLOPT_SSLCERT` option (`--cert` with the command line tool).When libcurl is built to use the macOS native TLS library Secure Transport, an application can ask for the client certificate by name or with a file name - using the same option. If the name exists as a file, it will be used instead of by name.If the appliction runs with a current working directory that is writable by other users (like `/tmp`), a malicious user can create a file name with the same name as the app wants to use by name, and thereby trick the application to use the file based cert instead of the one referred to by name making libcurl send the wrong client certificate in the TLS connection handshake.

• CWE-840Business Logic ErrorsWeaknesses in this category identify some of the underlying problems that commonly allow attackers to manipulate the business logic of an application. Errors in business logic can be devastating to an entire application. They can be difficult to find automatically, since they typically involve legitimate use of the application's functionality. However, many business logic errors can exhibit patterns that are similar to well-understood implementation and design weaknesses.
• CWE-295Improper Certificate ValidationThe product does not validate, or incorrectly validates, a certificate.