#VU79522 Time-of-check Time-of-use (TOCTOU) Race Condition in rpm - CVE-2021-35937

Vulnerability identifier: #VU79522

Vulnerability risk: Low

CVSSv4.0: 4.8 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-35937

CWE-ID: CWE-367

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
rpm

Vendor: rpm-software-management

Description

The vulnerability allows a local privileged user to escalate privileges on the system.

The vulnerability exist due to race condition. A local privileged user can bypass the checks that were introduced in response to CVE-2017-7500 and CVE-2017-7501, potentially gaining root privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

rpm: before 4.18.0

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=1964125
https://www.usenix.org/legacy/event/sec05/tech/full_papers/borisov/borisov.pdf
https://access.redhat.com/security/cve/CVE-2021-35937
https://rpm.org/wiki/Releases/4.18.0
https://security.gentoo.org/glsa/202210-22

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.