Redpanda v26.1.17

Bug Fixes

• Fixed an issue where audit-log initialization unconditionally sent a CreateTopics request to the controller leader, causing authentication and the admin API to be rejected cluster-wide (with audit_failure_policy=reject) for the duration of any prolonged leaderless state. Initialization now checks the local topic table first and skips the CreateTopics call when the audit topic already exists. by @andresaristizabal-rp in #31411
• Fixed an issue where backpressure from the Iceberg coordinator caused high CPU load on the Datalake translators. The translation loop was treating a backpressured fetch as a successful iteration and cancelling its retry jitter, causing it to spin as fast as the RPC completed rather than applying the normal jittered sleep. by @pgellert in #31419
• Reverted the c-ares DNS resolver from 1.34.7 back to 1.34.6. c-ares 1.34.7 contains an upstream regression (c-ares/c-ares#1256) where a DNS query completion callback can silently never be invoked, which could leave an internal broker-to-broker RPC connection permanently unable to reconnect after a peer broker restart. Affected clusters showed persistently under-replicated partitions and failing broker readiness probes. Reverting c-ares reintroduces CVE-2026-33630; the CVE fix will be re-applied once upstream resolves the regression. by @bartoszpiekny-redpanda in #31634

Full Changelog: https://github.com/redpanda-data/redpanda/compare/v26.1.16...v26.1.17