CVE-2026-35389: Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server

Q: How do I fix CVE-2026-35389?

webmail: upgrade to 1.4.11. Exact commands for each OS are on this page.

Q: Is CVE-2026-35389 being exploited?

CVE-2026-35389 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-35389 affect?

CVE-2026-35389 affects webmail. Severity is high (CVSS 7.5). 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 cert

Q: How urgent is CVE-2026-35389?

Priority 33/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-35389 is a high-severity flaw (CVSS 7.5) affecting webmail. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-295
Published	2026-04-06
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: bulwarkmail

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-06 21:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

bulwarkmail webmail UPGRADE

Affected: < 1.4.11

Fixed in: 1.4.11

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy webmail || rpm -q webmail || webmail --version

2. UPGRADE to 1.4.11 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade webmail

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade webmail

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-35389?

webmail: upgrade to 1.4.11. Exact commands for each OS are on this page.

Is CVE-2026-35389 being exploited?

CVE-2026-35389 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-35389 affect?

CVE-2026-35389 affects webmail. Severity is high (CVSS 7.5). 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 cert

How urgent is CVE-2026-35389?

Priority 33/100. High severity; Remotely exploitable, no login, no user action

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References

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