Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Affected: Go: code.gitea.io/gitea

## Vulnerability Header

| Field | Value | | ------------------- | ----------------------------------------------------------------------------------- | | Vulnerability Title | Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write | | Severity Rating | High | | Bug Category | Authorization Bypass | | Location | `routers/private/hook_pre_receive.go:55-64`, `CanWriteCode()` | | Affected Versions | 1.25.5 |

## Executive Summary

The pre-receive hook in Gitea evaluates the `CanMaintainerWriteToBranch` permission only once per `git push` session and caches the result for all subsequent refs in the same batch. An attacker who has a legitimate per-branch write grant (e.g., via an open pull request with "Allow edits from maintainers" enabled) can batch-push that branch together with any other ref. The cached `true` from the first ref is reused for all following refs, allowing the attacker to overwrite protected branches (including `main`), create arbitrary new branches, and push tags. This effectively escalates a single-branch maintainer-edit grant into full repository write access.

## Root Cause Anal…

Ein Angreifer kann mehrere Schwachstellen in Gitea ausnutzen, um erweiterte Berechtigungen zu erlangen, sich als Benutzer auszugeben, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren und vertrauliche Informationen offenzulegen.