CVE-2026-77463

Description

Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. From 1.0.0 until 1.16.2, Remark42 globally trusts True-Client-IP, X-Real-IP, and X-Forwarded-For without verifying that the direct peer is a trusted proxy, and middleware.RealIP overwrites r.RemoteAddr before per-IP controls run. In a directly reachable deployment, or a proxy that forwards attacker-controlled headers, a remote attacker can rotate spoofed forwarding headers to obtain fresh token buckets for rate-limited endpoints, bypass vote de-duplication when --votes-ip is enabled, mint anonymous identities, and poison stored comment IPs and request logs. The global concurrent-request throttle and per-request timeouts still limit availability impact. Mitigation support is available in version 1.16.2, but operators must configure --trusted-proxy for the deployment topology.

References

• https://github.com/umputun/remark42/commit/b1502801facd7782a1c70fd51f8ad5c2eb650d39
• https://github.com/umputun/remark42/commit/e62b3c830d81659cf5d2687b0c8261da7d42fdab
• https://github.com/umputun/remark42/pull/2116
• https://github.com/umputun/remark42/pull/2118
• https://github.com/umputun/remark42/releases/tag/backend/v1.16.2