CVE-2026-9818

✕ Withdrawn — historical dataMEDIUMPre-NVD 4.7
4.7CVSS
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 4.7Exploit: None knownExposed: 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
EchelonGraph score
Not yet assessedThis CVE record was withdrawn by its numbering authority, so there is no vulnerability to rate.
EG Score
—
EG Risk
—
EPSS PROB
—
EPSS %ILE
—
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 0× in last 7d / 6× 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. 2026-08-24 00:29 UTCGHSA enrichment
  2. 2026-08-20 17:38 UTCGHSA enrichment
  3. 2026-08-17 08:17 UTCGHSA enrichment
  4. 2026-08-14 01:03 UTCGHSA enrichment
  5. 2026-08-10 06:50 UTCGHSA enrichment
  6. 2026-08-07 00:06 UTCGHSA enrichment
  7. 2026-08-03 16:11 UTCGHSA enrichment
  8. 2026-07-31 06:21 UTCEG score recompute
  9. 2026-07-31 06:21 UTCGHSA enrichment
  10. 2026-07-27 09:41 UTCEG score recompute
  11. 2026-07-27 09:41 UTCGHSA enrichment
  12. 2026-07-23 03:23 UTCEG score recompute▼ 4.70
  13. 2026-07-16 10:17 UTCGHSA enrichment
  14. 2026-07-11 20:27 UTCGHSA enrichment
  15. 2026-07-08 18:12 UTCGHSA enrichment
  16. 2026-07-02 14:11 UTCGHSA enrichment
  17. 2026-07-01 03:02 UTCGHSA enrichment
  18. 2026-06-29 13:43 UTCGHSA enrichment
  19. 2026-06-28 12:06 UTCGHSA enrichment
  20. 2026-06-27 14:27 UTCGHSA enrichment
  21. 2026-06-26 16:49 UTCGHSA enrichment
  22. 2026-06-25 14:24 UTCGHSA enrichment
  23. 2026-06-24 16:46 UTCGHSA enrichment
  24. 2026-06-17 08:12 UTCGHSA enrichment
  25. 2026-06-16 10:34 UTCGHSA enrichment
Show 18 more
  1. 2026-06-15 12:55 UTCGHSA enrichment
  2. 2026-06-14 14:15 UTCGHSA enrichment
  3. 2026-06-13 16:37 UTCGHSA enrichment
  4. 2026-06-12 18:22 UTCGHSA enrichment
  5. 2026-06-11 20:44 UTCGHSA enrichment
  6. 2026-06-10 23:06 UTCGHSA enrichment
  7. 2026-06-10 01:28 UTCGHSA enrichment
  8. 2026-06-09 03:50 UTCGHSA enrichment
  9. 2026-06-08 06:12 UTCGHSA enrichment
  10. 2026-06-07 08:34 UTCGHSA enrichment
  11. 2026-06-06 10:56 UTCGHSA enrichment
  12. 2026-06-05 13:19 UTCGHSA enrichment
  13. 2026-06-04 15:41 UTCGHSA enrichment
  14. 2026-06-03 18:02 UTCGHSA enrichment
  15. 2026-06-02 20:24 UTCGHSA enrichment
  16. 2026-06-01 22:46 UTCGHSA enrichment
  17. 2026-06-01 01:08 UTCGHSA enrichment
  18. 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

Explore the affected products and dependency analysis for CVE-2026-9818

Explore →

Is Your Infrastructure Affected by CVE-2026-9818?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs