CVE-2026-103647
Cross-site scripting in the webmail of Progressive Robot hMailServer 6.3.2 through 6.3.5 allows a…
- Risk score
- 56/100
- CVSS
- 8.0 v3.1
- Exploit chance (30 days)
- 0.2%
- Published
- 8 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 …
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 8.0 high
- Remotely exploitable without logging in
References
Original description
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.
Last activity 8 Oct 2026. Patch Forecast updates every hour.