CVE-2026-70481: Open WebUI: Any member with write access to a standard channel can edit or delete other members' messages

On standard channels, the message update and delete handlers accepted any caller holding write access on the channel, without checking that the caller wrote the message. Write access is the same grant a member needs in order to post, so every ordinary participant in a shared channel could rewrite or permanently delete any other participant’s messages. The group and direct message branch of the same handlers enforced authorship; the standard branch did not.