| Package | Affected versions | Patched versions |
|---|---|---|
| org.postgresql:postgresql | ≥ 42.2.0, < 42.7.11 | 42.7.11 |
| postgresql jdbc driver | ≥ 42.2.0, < 42.7.11 | 42.7.11 |
pgjdbc is vulnerable to a client-side denial of service during SCRAM-SHA-256 authentication.
A malicious server can instruct the driver to perform SCRAM authentication with a very large iteration count. With a large enough value, the client spends an unbounded amount of CPU time inside PBKDF2 before authentication can fail. A single attempt ties up a CPU core. Repeated or concurrent attempts exhaust client CPU and can wedge connection pools.
In affected versions, loginTimeout did not fully mitigate this problem. When loginTimeout expired, the caller could stop waiting, but the worker thread performing the connection attempt could continue running and burning CPU inside the SCRAM PBKDF2 computation.
This issue affects availability. It does not provide authentication bypass, privilege escalation, or direct password disclosure.
A user is vulnerable when all of the following are true:
server-first-message.In practice, that can happen in these situations:
/etc/hosts, environment variables, or similar indirectionsslmode lower than verify-full, or trusting a CA that signs hosts outside the operator's control)The issue is more damaging when the application uses connection retries, many parallel connection attempts, or loginTimeout and assumes the timeout fully stops the work.
Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site freeThe patch introduces a new connection property, scramMaxIterations, with a default of 100K. The client now rejects SCRAM server messages that advertise more PBKDF2 iterations than the configured cap before starting the PBKDF2 computation begins.
Until a patched version of pgjdbc is deployed, the following measures reduce exposure:
Only connect to trusted PostgreSQL servers whose identity is verified.
Connect only to trusted PostgreSQL servers, and verify server identity with TLS using sslmode=verify-full and a trusted CA.
TLS without certificate and hostname verification is not sufficient as an active network attacker can still impersonate the server.
Do not rely on loginTimeout as a complete mitigation on unpatched versions.
On affected versions, loginTimeout can stop the waiting caller while the worker thread continues spending CPU.
Avoid SCRAM on untrusted or interceptable connection paths.
For those paths, use an authentication method that does not let the server choose a SCRAM PBKDF2 iteration count.
Reduce blast radius operationally.
Limit parallel connection attempts, add retry backoff, isolate connection establishment in a separate worker or process when possible, and apply CPU or container limits where appropriate.
On trusted servers you control, keep SCRAM iteration counts at ordinary values.
This does not defend against an attacker-controlled server, but it avoids unnecessary client cost when talking to legitimate servers.