CVE-2026-77463

Medium

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.

SeverityMedium
CVSS6.5
Exploit probability—
ProductUmputun Remark42
PublishedNov 5, 2026
First seenNov 5, 2026

How to fix

Sources list no fixed version or patch link for this vulnerability.

Affected products

ProductAffected versionsFixed in
umputun remark42>= 1.0.0, < 1.16.2—

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