DEBIAN-CVE-2026-40021: log4net security update

DEBIAN-CVE-2026-40021, released April 10, 2026, fixes 1 CVE in log4net (version 1.2.10+dfsg-10). None of them is reported as exploited. Patch Radar priority: Routine.

Routine

CVEs closed

None rated Critical

Exploited

None reported

Highest CVSS

5.3

Base score, 0 to 10

Highest EPSS

0.0080

56th percentile

Fixed package versions

Product	Release	Fixed in
log4net	Debian 14	1.2.10+dfsg-10

CVEs this fix closes

Priority	CVE	Title	CVSS	EPSS	Exploitation
Routine	CVE-2026-40021	log4net: Apache Log4net's XmlLayout https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list and Xm...	5.3	0.0080	None reported

Also fixes CVE-2026-40021

FEDORA-2026-588BC7E01C
log4net, log4net-devel, nant and 2 more on Fedora 43

Vendor advisory

https://security-tracker.debian.org/tracker/CVE-2026-40021

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