High 8.0Published Oct 8, 2026

CVE-2026-103647Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in hMailServer

Updated under an hour ago (2026-10-19 09:50 UTC)

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It affects Progressive Robot Ltd hMailServer. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.25%, higher than 15% of scored CVEs.

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Every CVE for Progressive Robot Ltd hMailServer

Exploited in the last 30 days

Cross-site scripting in the webmail of Progressive Robot hMailServer 6.3.2 through 6.3.5 allows a remote attacker who can send a user an encrypted message to run script in the webmail's origin with that user's session. When the webmail decrypted an S/MIME message (from 6.3.2) or an OpenPGP message (from 6.3.4) in the browser, it offered each decrypted attachment as a blob URL of the media type the message declared for it. A click saved the file, but if the user opened the attachment in a new tab, a part declared as text/html was rendered as a document of the webmail's origin and its script could read the mailbox, send mail and change the account through the REST API. The webmail is served only when the REST API is enabled, which it is not by default.

CVSS: 8.0 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.25% (percentile 15)
Assigned by: GitLab
NVD analysis: Deferred
Record last updated: Oct 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Progressive Robot Ltd hMailServer progressive_robot:hmailserver (from the name)	from 6.3.2 before 6.3.6	CNA record

References

https://gitlab.com/hmailserver/hmailserver/-/work_items/52
https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.