Summary

gRPC access loggers using the listener's global scope can cause a use-after-free crash when the listener is drained.

Impacted Component

opentelemetry/gRPC access logger extension

Details

If the listener is drained while the cached gRPC access logger is still using the listener's global scope for stats, a use-after-free will cause Envoy to crash

PoC

• Envoy starts serving the traffic with listener and gRPC access log setting.
• LDS update modifies the listener, causing the previous one to be drained. If the config has the same gRPC access logger it is not removed from the cache.
• A new request comes in, and the gRPC access logger is still referencing the previous listeners' scope for stats causing a crash.

Attack vector(s)

Untrusted LDS upstream.

Impact

Denial of service and rejection of requests.

Mitigation

Disable gRPC access log or stop listener update

Credits

William Sears wsears@akamai.com