temporalio/sqlparser can panic when Parse, ParseStrictDDL, or ParseNext processes a MySQL version comment whose contents are empty or consist only of one to five decimal digits. ExtractMysqlComment does not check the -1 result returned by strings.IndexFunc before using it as a slice boundary. The resulting Go runtime panic propagates unless the caller recovers it on the parsing goroutine, so applications that parse attacker-controlled SQL can terminate. Temporal Server exposes the affected parser through ListWorkers. When that API is enabled, an authenticated caller with namespace read permission can submit a malformed query that terminates the receiving Matching process. Repeated requests can sustain a denial of service. The issue affects availability only; no confidentiality or integrity impact was identified.
In Temporal Server 1.29.x, ListWorkers reaches the vulnerable parser only when frontend.ListWorkersEnabled is enabled; the setting defaults to false. In 1.30.x, the setting defaults to true. Beginning in 1.31.0, the setting remains defined but is no longer honored, and ListWorkers is always enabled. In supported authenticated deployments, ListWorkers requires namespace read permission.
Until upgrading, applications can reject MySQL version comments before invoking the parser or recover parser panics on the parsing goroutine. Temporal Server 1.29 and 1.30 operators can set frontend.ListWorkersEnabled to false. On any affected Server release, restrict ListWorkers to trusted principals or apply the matching-handler panic-recovery change as interim containment. Panic recovery does not replace the parser fix.
Upgrade github.com/temporalio/sqlparser to v0.0.0-20260721183040-74181ffcbaaf or later. Temporal Server operators should upgrade to 1.30.7, 1.31.3, or 1.32.0, as appropriate for the deployed minor release line. The parser fix treats MySQL version comments as ordinary comments instead of interpreting their contents as SQL.