CVE-2026-9818

✕ Withdrawn — historical dataMEDIUMPre-NVD 4.74.7—
EchelonGraph scoreMEDIUM confidence

Score 4.7 from GitHub Security Advisory published 2026-05-28. the CNA's CVSS baseline 4.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:ocd, ghsa
4.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: —CVSS: 4.7Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Roundcube's HTML sanitization path for message rendering allows loopback, localhost, RFC1918, link-local, and ULA URLs even when remote content loading is disabled. A remote attacker can send an HTML email that causes the victim's browser to issue requests to local or private-network services simply by opening the message preview.

CVSS v3
4.7
EG Score
4.7(medium)
EPSS
—
KEV
Not listed

Published

May 28, 2026

Last Modified

May 28, 2026

Advisory Details (5)

Auto-updated Jun 13, 2026
Patch available. Sources: github_release, github_commit.
generic

Orange Cyberdefense Security Advisories

https://advisories.orangecyberdefense.com/advisories/163
github_commit

commit 7b52353653a6 (roundcube/roundcubemail)

Fix landed in roundcube/roundcubemail commit 7b52353653a6 — awaiting tagged release

https://github.com/roundcube/roundcubemail/commit/7b52353653a67e6073b97d70eb94047132b78556
github_commit

commit faf867432f51 (roundcube/roundcubemail)

Fix landed in roundcube/roundcubemail commit faf867432f51 — awaiting tagged release

https://github.com/roundcube/roundcubemail/commit/faf867432f51ebbe100382a70a9e3c042415ee1b
github_release Patch Available

Roundcube Webmail 1.6.16

Patch available: roundcube/roundcubemail 1.6.16

https://github.com/roundcube/roundcubemail/releases/tag/1.6.16
github_release Patch Available

Roundcube Webmail 1.7.1

Patch available: roundcube/roundcubemail 1.7.1

https://github.com/roundcube/roundcubemail/releases/tag/1.7.1

Vendor Advisories for CVE-2026-9818(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 4× in last 7d / 24× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-16 10:17 UTCEG score recompute
  2. 2026-07-16 10:17 UTCGHSA enrichment
  3. 2026-07-11 20:27 UTCEG score recompute
  4. 2026-07-11 20:27 UTCGHSA enrichment
  5. 2026-07-08 18:12 UTCEG score recompute
  6. 2026-07-08 18:12 UTCGHSA enrichment
  7. 2026-07-02 14:11 UTCEG score recompute
  8. 2026-07-02 14:11 UTCGHSA enrichment
  9. 2026-07-01 03:02 UTCEG score recompute
  10. 2026-07-01 03:02 UTCGHSA enrichment
  11. 2026-06-29 13:43 UTCEG score recompute
  12. 2026-06-29 13:43 UTCGHSA enrichment
  13. 2026-06-28 12:07 UTCEG score recompute
  14. 2026-06-28 12:06 UTCGHSA enrichment
  15. 2026-06-27 14:27 UTCEG score recompute
  16. 2026-06-27 14:27 UTCGHSA enrichment
  17. 2026-06-26 16:49 UTCEG score recompute
  18. 2026-06-26 16:49 UTCGHSA enrichment
  19. 2026-06-25 14:24 UTCEG score recompute
  20. 2026-06-25 14:24 UTCGHSA enrichment
  21. 2026-06-24 16:46 UTCEG score recompute
  22. 2026-06-24 16:46 UTCGHSA enrichment
  23. 2026-06-17 08:12 UTCEG score recompute
  24. 2026-06-17 08:12 UTCGHSA enrichment
  25. 2026-06-16 10:34 UTCEG score recompute
Show 36 more
  1. 2026-06-16 10:34 UTCGHSA enrichment
  2. 2026-06-15 12:56 UTCEG score recompute
  3. 2026-06-15 12:55 UTCGHSA enrichment
  4. 2026-06-14 14:15 UTCEG score recompute
  5. 2026-06-14 14:15 UTCGHSA enrichment
  6. 2026-06-13 16:37 UTCEG score recompute
  7. 2026-06-13 16:37 UTCGHSA enrichment
  8. 2026-06-12 18:22 UTCEG score recompute
  9. 2026-06-12 18:22 UTCGHSA enrichment
  10. 2026-06-11 20:44 UTCEG score recompute
  11. 2026-06-11 20:44 UTCGHSA enrichment
  12. 2026-06-10 23:06 UTCEG score recompute
  13. 2026-06-10 23:06 UTCGHSA enrichment
  14. 2026-06-10 01:28 UTCEG score recompute
  15. 2026-06-10 01:28 UTCGHSA enrichment
  16. 2026-06-09 03:51 UTCEG score recompute
  17. 2026-06-09 03:50 UTCGHSA enrichment
  18. 2026-06-08 06:12 UTCEG score recompute
  19. 2026-06-08 06:12 UTCGHSA enrichment
  20. 2026-06-07 08:34 UTCEG score recompute
  21. 2026-06-07 08:34 UTCGHSA enrichment
  22. 2026-06-06 10:57 UTCEG score recompute
  23. 2026-06-06 10:56 UTCGHSA enrichment
  24. 2026-06-05 13:19 UTCEG score recompute
  25. 2026-06-05 13:19 UTCGHSA enrichment
  26. 2026-06-04 15:41 UTCEG score recompute
  27. 2026-06-04 15:41 UTCGHSA enrichment
  28. 2026-06-03 18:02 UTCEG score recompute
  29. 2026-06-03 18:02 UTCGHSA enrichment
  30. 2026-06-02 20:24 UTCEG score recompute
  31. 2026-06-02 20:24 UTCGHSA enrichment
  32. 2026-06-01 22:46 UTCEG score recompute
  33. 2026-06-01 22:46 UTCGHSA enrichment
  34. 2026-06-01 01:08 UTCEG score recompute
  35. 2026-06-01 01:08 UTCGHSA enrichment
  36. 2026-05-28 12:43 UTCEG score recompute

Frequently asked(4)

What is CVE-2026-9818?
CVE-2026-9818 is a medium vulnerability published on May 28, 2026. Roundcube's HTML sanitization path for message rendering allows loopback, localhost, RFC1918, link-local, and ULA URLs even when remote content loading is disabled. A remote attacker can send an HTML email that causes the victim's browser to issue requests to local or private-network services…
When was CVE-2026-9818 disclosed?
CVE-2026-9818 was first published in the National Vulnerability Database on May 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-9818?
CVE-2026-9818 has a CVSS v4.0 base score of 4.7 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-9818?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-9818, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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