In KDE KMail 19.12.3 (aka 5.13.3), the SMTP STARTTLS option is not honored (and cleartext messages are sent) unless "Server requires authen…

published 2021-08-10 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24826

cvss: 5.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits: 0; none known

In KDE KMail 19.12.3 (aka 5.13.3), the SMTP STARTTLS option is not honored (and cleartext messages are sent) unless "Server requires authentication" is checked.

Patch / fix

distros 2

debian arch linux

ksmtp Debian 14, Debian 13, Debian 12 21.12.3-2

debian advisories DEBIAN-CVE-2021-38373

ksmtp Arch Linux 21.12.0-1

arch linux advisories AVG-2274

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-38373 updated 2026-11-07 cvss 6.5

kmail: STARTTLS is ignored when "Server requires authentication" not checked in UI

Red Hat Enterprise Linux 6 kdepim, kdepim-libs, kdepim3-libs Red Hat Enterprise Linux 7 kdepim, kdepim-libs
affected: no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.53% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.3	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD	2.0	3.5	AV:N/AC:M/Au:S/C:P/I:N/A:N

Classification

Weakness

CWE-77 Improper Neutralization of Special Elements used in a Command
CWE-319 Cleartext Transmission of Sensitive Information

References

bugs.kde.org /show_bug.cgi?id=423423
mailing-list, vendor-advisory
nostarttls.secvuln.info
third-party-advisory

Sources

CVE List CVE-2021-38373
NVD CVE-2021-38373

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary