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CVE-2026-9818

Roundcube Local/Private URL Fetch Bypass

Published: May 28, 2026Updated: May 28, 2026 Sources: CVE List NVD
NVD MITRE
4.7CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:CC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None

Weaknesses

CWE-184

Affected Products

Webmail
Roundcube

Exploitability

Official Patch Available

References

https://advisories.orangecyberdefense.com/advisories/163
advisories.orangecyberdefense.com
https://github.com/roundcube/roundcubemail/commit/7b52353653a67e6073b97d70eb94047132b78556
github.com
https://github.com/roundcube/roundcubemail/commit/faf867432f51ebbe100382a70a9e3c042415ee1b
github.com
and 2 more references View all →

Timeline

Published
May 28, 2026
Last Updated
May 28, 2026

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