Known exploited vulnerability
CVE-2021-4034
The short answer
CVE-2021-4034 affects n/a polkit and is rated high (CVSS 7.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2022-06-27: attackers are using it, so patch it first. The vendor has linked a patch.
What it is
A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine.
Severity
7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Jun 27, 2022
Federal due date Jul 18, 2022
EPSS, next 30 days
95%
Higher than 100% of scored CVEs
How it can be exploited
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply updates per vendor instructions.
Affected products
polkit. NVD's record lists the exact affected versions.
References
- access.redhat.com/security/vulnerabilities/RHSB-2022-001 MitigationVendor Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2025869 Issue TrackingPatch
- cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf Third Party Advisory
- gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683 Patch
- www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
- www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt ExploitMitigationThird Party Advisory
- www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/ ExploitThird Party Advisory
- www.starwindsoftware.com/security/sw-20220818-0001/ Third Party Advisory
- www.suse.com/support/kb/doc/?id=000020564 Third Party Advisory
- access.redhat.com/security/vulnerabilities/RHSB-2022-001 MitigationVendor Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2025869 Issue TrackingPatch
- cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf Third Party Advisory
Questions
Is CVE-2021-4034 being exploited?
Yes. CISA added CVE-2021-4034 to its Known Exploited Vulnerabilities catalog on 2022-06-27, with a federal remediation due date of 2022-07-18. CISA lists it as used in ransomware campaigns.
How do I fix CVE-2021-4034?
CISA's required action: Apply updates per vendor instructions.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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