GHSA-857q-xmph-p2v5 s2n-tls's mTLS API ordering may skip client authentication
An API ordering flaw in s2n-tls may skip client authentication, allowing unauthorized access if specific configuration calls are made in the wrong order.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-857q-xmph-p2v5?
GHSA-857q-xmph-p2v5 is an authentication bypass vulnerability in s2n-tls, published on 9 Aug 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Impact
An API ordering issue in s2n-tls can cause client authentication to unexpectedly not be enabled on the server when it otherwise appears to be. Server applications are impacted if client authentication is enabled by calling s2n_connection_set_config() before calling s2n_connection_set_client_auth_type().
Applications are not impacted if these APIs are called in the opposite order, or if client authentication is enabled on the config with s2n_config_set_client_auth_type(). s2n-tls clients verifying server certificates are not impacted.
Impacted versions: < v1.5.0.
Patches
The patch is included in v1.5.0 [1].
Workarounds
Applications can workaround this issue by calling s2n_connection_set_config() after calling s2n_connection_set_client_auth_type(), or by enabling client authentication on the config with s2n_config_set_client_auth_type().
If you have any questions or comments about this advisory we ask that you contact AWS/Amazon Security via our vulnerability reporting page [2] or directly via email to [email protected]. Please do not create a public GitHub issue.
Which versions are affected by GHSA-857q-xmph-p2v5?
2 open source packages ship an affected version, including s2n-tls.
| Package | Affected | Fixed in |
|---|---|---|
s2n-tls crates.io | All versions | 0.3.0 |
s2n-tls crates.io | All versions | 0.3.0 |
How do I fix GHSA-857q-xmph-p2v5?
Upgrade s2n-tls to 0.3.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is GHSA-857q-xmph-p2v5 being exploited?
There is no known exploitation of GHSA-857q-xmph-p2v5 in the wild and no public exploit code.