Executive brief
Higress is an AI-native API gateway that enforces token-based rate limits to control expensive model API calls. A defect in Cookie header parsing can be exploited by sending a malformed Cookie without proper formatting, causing the rate-limiting plugin to crash and recover in a permissive state that allows requests to bypass rate limits, enabling attackers to exceed intended thresholds without authentication.
Technical details
The vulnerability is a denial-of-service/auth-bypass in the ai-token-ratelimit WASM plugin. The root cause is unsafe parsing in the ExtractCookieValueByKey function in util/utils.go, which splits cookie pairs on "=" without validating that the split produces at least two elements. A Cookie header segment lacking an equals sign causes an index-out-of-bounds panic. When the plugin wrapper catches this panic, it returns a "continue" action instead of enforcing the rate limit, allowing the request through. This is a network-reachable vulnerability requiring no authentication; an attacker sends a crafted malformed Cookie header to skip rate-limit checks. Affected versions: before 2.2.4. The fix is to validate split results before indexing.
Affected products
- Higress Higress before 2.2.4
Timeline
- 2026-09-16: disclosed