GHSA-f5v5-ccqc-6w36
async-nats vulnerable to TLS certificate common name validation bypass
GHSA-f5v5-ccqc-6w36 is a vulnerability with no CVSS score yet in async-nats, published March 24, 2023. No source lists public exploit code. Fixed in async-nats 0.29.0.
- Severity
- UnratedNo CVSS score yet
- Exploit chance
- UnscoredNo EPSS score yet
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
0.29.0async-nats +1 more
Description
The NATS official Rust clients are vulnerable to MitM when using TLS.
The common name of the server's TLS certificate is validated against the hostname provided by the server's plaintext INFO message during the initial connection setup phase. A MitM proxy can tamper with the host field's value by substituting it with the common name of a valid certificate it controls, fooling the client into accepting it.
Reproduction steps
- The NATS Rust client tries to establish a new connection
- The connection is intercepted by a MitM proxy
- The proxy makes a separate connection to the NATS server
- The NATS server replies with an
INFOmessage - The proxy reads the
INFO, alters thehostJSON field and passes the tamperedINFOback to the client - The proxy upgrades the client connection to TLS, presenting a certificate issued by a certificate authority present in the client's keychain. In the previous step the
hostwas set to the common name of said certificate rustlsaccepts the certificate, having verified that the common name matches the attacker-controlled value it was given- The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate
Affected packages
| Package | Affected | Fixed |
|---|---|---|
async-natscrates.io | before 0.29.0 | 0.29.0 |
async-natscrates.io | 0.0.0-0 up to 0.29.0 | 0.29.0 |
What each source reports
GitHub AdvisoriesNo score
async-nats vulnerable to TLS certificate common name validation bypass
The NATS official Rust clients are vulnerable to MitM when using TLS.
The common name of the server's TLS certificate is validated against the hostname provided by the server's plaintext INFO message during the initial connection setup phase. A MitM proxy can tamper with the host field's value by substituting it with the common name of a valid certificate it controls, fooling the client into accepting it.
Reproduction steps
- The NATS Rust client tries to establish a new connection
- The connection is intercepted by a MitM proxy
- The proxy makes a separate connection to the NATS server
- The NATS server replies with an
INFOmessage - The proxy reads the
INFO, alters thehostJSON field and passes the tamperedINFOback to the client - The proxy upgrades the client connection to TLS, presenting a certificate issued by a certificate authority present in the client's keychain. In the previous step the
hostwas set to the common name of said certificate rustlsaccepts the certificate, having verified that the common name matches the attacker-controlled value it was given- The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate
- Record
GHSA-f5v5-ccqc-6w36- Updated
- 2026-11-02
OSVNo score
async-nats vulnerable to TLS certificate common name validation bypass
The NATS official Rust clients are vulnerable to MitM when using TLS.
The common name of the server's TLS certificate is validated against the hostname provided by the server's plaintext INFO message during the initial connection setup phase. A MitM proxy can tamper with the host field's value by substituting it with the common name of a valid certificate it controls, fooling the client into accepting it.
Reproduction steps
- The NATS Rust client tries to establish a new connection
- The connection is intercepted by a MitM proxy
- The proxy makes a separate connection to the NATS server
- The NATS server replies with an
INFOmessage - The proxy reads the
INFO, alters thehostJSON field and passes the tamperedINFOback to the client - The proxy upgrades the client connection to TLS, presenting a certificate issued by a certificate authority present in the client's keychain. In the previous step the
hostwas set to the common name of said certificate rustlsaccepts the certificate, having verified that the common name matches the attacker-controlled value it was given- The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate
- Record
GHSA-f5v5-ccqc-6w36- Updated
- 2026-11-02
OSVRUSTSEC-2023-0027No score
TLS certificate common name validation bypass
The NATS official Rust clients are vulnerable to MitM when using TLS.
The common name of the server's TLS certificate is validated against
the hostname provided by the server's plaintext INFO message
during the initial connection setup phase. A MitM proxy can tamper with
the host field's value by substituting it with the common name of a
valid certificate it controls, fooling the client into accepting it.
Reproduction steps
- The NATS Rust client tries to establish a new connection
- The connection is intercepted by a MitM proxy
- The proxy makes a separate connection to the NATS server
- The NATS server replies with an
INFOmessage - The proxy reads the
INFO, alters thehostJSON field and passes the tamperedINFOback to the client - The proxy upgrades the client connection to TLS, presenting a certificate issued
by a certificate authority present in the client's keychain.
In the previous step the
hostwas set to the common name of said certificate rustlsaccepts the certificate, having verified that the common name matches the attacker-controlled value it was given- The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate
- Record
RUSTSEC-2023-0027- Updated
- 2026-11-02
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | GitHub Advisories, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.