What is CVE-2021-3939?

CVE-2021-3939 is a high-severity vulnerability in Canonical Accountsservice, classified under CWE-590. CVSS score: 7.8/10. Published 2021-11-17.

How severe is CVE-2021-3939?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in Canonical Accountsservice

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.

Published 2021-11-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (29.8th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 29.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Canonical Accountsservice
Canonical Ubuntu Linux — versions 20.04, 21.04, 21.10
Ubuntu Accountsservice — versions 0.6.55-0ubuntu12~20.04, 0.6.55-0ubuntu13, 0.6.55-0ubuntu14

Weakness classification (CWE)

References

ubuntu.com/security/notices/USN-5149-1 (Vendor Advisory)
bugs.launchpad.net/ubuntu/+source/accountsservice/+bug/1950149 (Broken Link)
packetstormsecurity.com/files/172848/Ubuntu-accountsservice-Double-Free-Memory-…

Frequently asked questions

What is CVE-2021-3939?: CVE-2021-3939 is a high-severity vulnerability in Canonical Accountsservice, classified under CWE-590. CVSS score: 7.8/10. Published 2021-11-17.
How severe is CVE-2021-3939?: High severity. CVSS v3 base score is 7.8 out of 10.