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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

8 Oct 2026 10:53:05 UTC

Source modified

8 Oct 2026 14:22:56 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 8.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N