Skip to main content
HIGH

CVE-2026-103649

CVSS v3

7.5

HIGH

EPSS Score

—

exploit probability

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

Missing network timeouts in the Linux builds of Progressive Robot hMailServer 6.3.0 through 6.3.5 allow a remote attacker to hold server threads indefinitely and so stop outbound mail delivery (denial of service). The server set its socket timeouts in the form Windows takes, which Linux refuses, and its HTTPS clients read without a deadline, so a peer that accepts a connection and then sends nothing held the waiting thread for as long as the connection stayed open. The MTA-STS policy fetch, enab

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-10-08
Last Modified
2026-10-08

Frequently asked questions

What is CVE-2026-103649?

Missing network timeouts in the Linux builds of Progressive Robot hMailServer 6.3.0 through 6.3.5 allow a remote attacker to hold server threads indefinitely and so stop outbound mail delivery (denial of service). The server set its socket timeouts in the form Windows takes, which Linux refuses, and its HTTPS clients read without a deadline, so a peer that accepts a connection and then sends nothing held the waiting thread for as long as the connection stayed open. The MTA-STS policy fetch, enab

Is CVE-2026-103649 actively exploited?

Active exploitation of CVE-2026-103649 has not been confirmed.

What is the CVSS score for CVE-2026-103649?

CVE-2026-103649 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Is CVE-2026-103649 affecting your environment?

Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.

Check an IPSearch CVEsSIEM & TIP integrations

No credit card required · 50 free checks/month · Free API key

Other 2026 vulnerabilities worth triaging

Ranked by exploit probability (EPSS).

Back to CVE Database