What’s Vulnerable › Vulnerabilities

CVE-2021-3939: Free of static data in accountsservice

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-11-17 · updated 2026-06-17
• Weakness: CWE-590

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.

Affected products

• Canonical accountsservice: from 0.6.55-0ubuntu12\~20.04 before 0.6.55-0ubuntu12\~20.05; from 0.6.55-0ubuntu13 before 0.6.55-0ubuntu13.3; from 0.6.55-0ubuntu14 before 0.6.55-0ubuntu14.1 — fixed in 0.6.55-0ubuntu12\~20.05, 0.6.55-0ubuntu13.3, 0.6.55-0ubuntu14.1
• Canonical Ubuntu Linux: 20.04, 21.04, 21.10

How to fix

Upgrade to a fixed version: Canonical accountsservice 0.6.55-0ubuntu12\~20.05, 0.6.55-0ubuntu13.3, 0.6.55-0ubuntu14.1. Check the vendor advisory for mitigations.

References

• http://packetstormsecurity.com/files/172848/Ubuntu-accountsservice-Double-Free-Memory-Corruption.html
• https://bugs.launchpad.net/ubuntu/+source/accountsservice/+bug/1950149
• https://ubuntu.com/security/notices/USN-5149-1
• http://packetstormsecurity.com/files/172848/Ubuntu-accountsservice-Double-Free-Memory-Corruption.html
• https://bugs.launchpad.net/ubuntu/+source/accountsservice/+bug/1950149
• https://ubuntu.com/security/notices/USN-5149-1

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