CVE-2021-22926 Security feature bypass in https://github.com/curl/curl
Attackers can trick libcurl into using a malicious certificate file if the application runs in a writable directory, bypassing intended TLS authentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-22926?
CVE-2021-22926 is a high-severity vulnerability in Haxx Curl, published on 5 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2021-22926?
It affects 19 products.
Products include Haxx Curl, Netapp Active Iq Unified Manager, Netapp Clustered Data Ontap, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410s Firmware and 13 more.
How do I fix CVE-2021-22926?
Apply the vendor's patch.
Is CVE-2021-22926 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-22926 exists.
Other vulnerabilities in Haxx Curl
Sources
Also known as ALPINE-CVE-2021-22926, AZL-6364, CURL-CVE-2021-22926, ECHO-c377-ec84-0da8, GHSA-5xph-62q2-pxff, JLSEC-2026-1338.