CVE-2026-77463Remark42: Rate limit bypass via unconditional trust of X-Forwarded-For/X-Real-IP headers in direct-internet deployment
- 6.5MediumCVSS base score
- 0.22%Exploitation in 30 daysEPSS · top 87% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://github.com/umputun/remark42/security/advisories/GHSA-56x6-q882-mf27 (opens in a new tab)x_refsource_CONFIRMexploit
Timeline
ID reserved
By GitHub_M
- 3 months later
· 3 months later
Published
- 5 days later
· 5 days later
Public exploit appeared
A proof of concept or exploit was published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
| NVDNVD · Deferred | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
- EPSS (exploitation in 30 days)
- 0.22% · top 87% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/umputun/remark42GHSA-56x6-q882-mf27 (opens in a new tab)
- Gogithub.com/umputun/remark42/backendGHSA-56x6-q882-mf27 (opens in a new tab)
References
References7
- https://github.com/umputun/remark42/security/advisories/GHSA-56x6-q882-mf27 (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/umputun/remark42/pull/2116 (opens in a new tab)x_refsource_MISC
- https://github.com/umputun/remark42/pull/2118 (opens in a new tab)x_refsource_MISC
- https://github.com/umputun/remark42/commit/b1502801facd7782a1c70fd51f8ad5c2eb650d39 (opens in a new tab)x_refsource_MISC
- https://github.com/umputun/remark42/commit/e62b3c830d81659cf5d2687b0c8261da7d42fdab (opens in a new tab)x_refsource_MISC
- https://github.com/umputun/remark42/releases/tag/backend/v1.16.2 (opens in a new tab)x_refsource_MISC
- https://remark42.com/docs/configuration/parameters/#trusted-proxies-and-client-ip (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-117799 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-56x6-q882-mf27 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-77463)Record last updated .