CVE-2021-3996

Summary

A logic error was found in the libmount library of util-linux in the function that allows an unprivileged user to unmount a FUSE filesystem. This flaw allows a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.

Affected Software

Weaknesses

• CWE-552: CWE-552 - Files or Directories Accessible to External Parties

ADP Enrichment

CVE Program Container

Additional References

• https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
• https://github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae637f4cdb
• https://www.openwall.com/lists/oss-security/2022/01/24/2
• https://bugzilla.redhat.com/show_bug.cgi?id=2024628
• https://access.redhat.com/security/cve/CVE-2021-3996
• http://www.openwall.com/lists/oss-security/2022/11/30/2
• http://seclists.org/fulldisclosure/2022/Dec/4
• http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html
• https://security.netapp.com/advisory/ntap-20221209-0002/
• https://security.gentoo.org/glsa/202401-08

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: partial

References

• https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
• https://github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae637f4cdb
• https://www.openwall.com/lists/oss-security/2022/01/24/2
• https://bugzilla.redhat.com/show_bug.cgi?id=2024628
• https://access.redhat.com/security/cve/CVE-2021-3996
• http://www.openwall.com/lists/oss-security/2022/11/30/2
• http://seclists.org/fulldisclosure/2022/Dec/4
• http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html
• https://security.netapp.com/advisory/ntap-20221209-0002/
• https://security.gentoo.org/glsa/202401-08

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