CVE-2021-3939: Ubuntu-specific modifications to accountsservice (in patch file debian/patches/0010-set-language.patch) caused the fallback_locale variable, pointing ...

Description

Ubuntu-specific modifications to accountsservice (in patch file debian/patches/0010-set-language.patch) caused the fallback_locale variable, pointing to static storage, to be freed, in the user_change_language_authorized_cb function. This is reachable via the SetLanguage dbus function. This is fixed in versions 0.6.55-0ubuntu12~20.04.5, 0.6.55-0ubuntu13.3, 0.6.55-0ubuntu14.1.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.35%

26.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Canonical	Accountsservice	>= 0.6.55-0ubuntu12\~20.04, < 0.6.55-0ubuntu12\~20.05
Canonical	Accountsservice	>= 0.6.55-0ubuntu13, < 0.6.55-0ubuntu13.3
Canonical	Accountsservice	>= 0.6.55-0ubuntu14, < 0.6.55-0ubuntu14.1
Canonical	Ubuntu Linux	20.04
Canonical	Ubuntu Linux	21.04
Canonical	Ubuntu Linux	21.10

References

Timeline

Published: Nov 17, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3939?

Ubuntu-specific modifications to accountsservice (in patch file debian/patches/0010-set-language.patch) caused the fallback_locale variable, pointing to static storage, to be freed, in the user_change_language_authorized_cb function. This is reachable via the SetLanguage dbus function. This is fixed in versions 0.6.55-0ubuntu12~20.04.5, 0.6.55-0ubuntu13.3, 0.6.55-0ubuntu14.1.

How severe is CVE-2021-3939?

CVE-2021-3939 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.35% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3939?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.