EUVD-2026-19478
CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3Description
Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.4.11, S/MIME signature verification did not validate the certificate trust chain (checkChain: false). Any email signed with a self-signed or untrusted certificate was displayed as having a valid signature. This vulnerability is fixed in 1.4.11.
Analysis
S/MIME signature verification in Bulwark Webmail prior to 1.4.11 fails to validate certificate trust chains, allowing attackers to forge digitally signed emails using self-signed or untrusted certificates that appear legitimate to recipients. This integrity bypass affects all unauthenticated remote attackers (CVSS:4.0 AV:N/AC:L/PR:N) with high integrity impact. …
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Remediation
Within 24 hours: Verify your Bulwark Webmail version and confirm whether it is prior to 1.4.11; immediately notify users of the integrity risk and recommend caution with digitally signed emails. Within 7 days: Contact Bulwark vendor for patch timeline confirmation and interim mitigation guidance; if version 1.4.11 or later becomes available, test in staging environment. …
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External POC / Exploit Code
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