# CVE-2026-77463: Remark42: Rate limit bypass via unconditional trust of X-Forwarded-For/X-Real-IP headers in direct-internet deployment

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- umputun / remark42: >= 1.0.0, < 1.16.2 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-348, CWE-807

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/umputun/remark42/security/advisories/GHSA-56x6-q882-mf27 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/umputun/remark42/pull/2116 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/umputun/remark42/pull/2118 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/umputun/remark42/commit/b1502801facd7782a1c70fd51f8ad5c2eb650d39 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/umputun/remark42/commit/e62b3c830d81659cf5d2687b0c8261da7d42fdab (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/umputun/remark42/releases/tag/backend/v1.16.2 (CNA: GitHub_M; x_refsource_MISC)

- https://remark42.com/docs/configuration/parameters/#trusted-proxies-and-client-ip (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-77463; retrieved 2026-11-05; source updated 2026-11-05

Revision: 7d3fcd8c4155b032945a8b1b959694f7e08d10f55f8fa03b2f616c8812ca4c91

Canonical: https://y2.dev/cve/CVE-2026-77463

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