CVE Intelligence
CISA KEV High Memory corruption exploit reference

CVE-2021-4034 — Red Hat Polkit Out-of-Bounds Read and Write Vulnerability

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.

Published Jan 28, 2022 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: redhat

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Jun 27, 2022 R used by ransomware (CISA) Metasploit modules · 1Exploit-DB · 1Proofs of concept on GitHub · 183
How the score was calculated
  • Confirmed exploitation (CISA KEV)+35
  • Used in ransomware campaigns (CISA)+10
  • Public exploit/PoC (metasploit, exploitdb, github)+20
  • EPSS 94.9% (30-day exploitation probability)+15
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Confirmed
CISA KEV, listed Jun 27, 2022
EPSS FIRST
94.92%
ahead of 100% of scored CVEs · Oct 14, 2026
Affects
Canonical
Ubuntu Linux and 29 more
CVSS base
7.8
High · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Active
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Jul 18, 2022 — passed 1550 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Canonical Ubuntu Linux, Oracle Http Server, Oracle Zfs Storage Appliance Kit…).
  2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
  3. Apply the fixed version or the patch documented under Remediation.
  4. EPSS ahead of 100% of scored CVEs: prioritize it in the patch queue.
  5. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Canonical Ubuntu Linux version 14.04version 16.04version 18.04version 20.04version 21.10 Vulnerable NIST National Vulnerability Database
Oracle Http Server version 12.2.1.4.0version 12.2.1.3.0 Vulnerable NIST National Vulnerability Database
Oracle Zfs Storage Appliance Kit version 8.8 Vulnerable NIST National Vulnerability Database
Polkit Project Polkit < 121 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux version 8.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Desktop version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Eus version 8.2 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Ibm Z Systems version 7.0version 8.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Ibm Z Systems Eus version 8.2version 8.4 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Power Big Endian version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Power Little Endian version 7.0version 8.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Power Little Endian Eus version 8.1version 8.4version 8.2 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux For Scientific Computing version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server version 6.0version 7.0 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Aus version 8.4version 8.2version 7.6version 7.4version 7.3version 7.7 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Eus version 8.4 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Tus version 7.6version 7.7version 8.2version 8.4 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Server Update Services For Sap Solutions version 8.2version 8.4version 8.1version 7.7version 7.6 Vulnerable NIST National Vulnerability Database
Red Hat Enterprise Linux Workstation version 7.0 Vulnerable NIST National Vulnerability Database
Siemens Scalance Lpe9403 Firmware < 2.0 Vulnerable NIST National Vulnerability Database
Siemens Sinumerik Edge < 3.3.0 Vulnerable NIST National Vulnerability Database
Starwindsoftware Command Center version 1.0-update3_build5871 Vulnerable NIST National Vulnerability Database
Starwindsoftware Starwind Virtual San version v8-build14338 Vulnerable NIST National Vulnerability Database
SUSE Enterprise Storage version 7.0 Vulnerable NIST National Vulnerability Database
SUSE Linux Enterprise Desktop version 15-sp2 Vulnerable NIST National Vulnerability Database
SUSE Linux Enterprise High Performance Computing version 15.0-sp2 Vulnerable NIST National Vulnerability Database
SUSE Linux Enterprise Server version 15-sp2 Vulnerable NIST National Vulnerability Database
SUSE Linux Enterprise Workstation Extension version 12-sp5 Vulnerable NIST National Vulnerability Database
SUSE Manager Proxy version 4.1 Vulnerable NIST National Vulnerability Database
SUSE Manager Server version 4.1 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.8 CVSS 3.1 High 1.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
7.8 CVSS 3.1 High 1.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
7.8 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.8 CVSS 3.1 High — — CISA-ADP via CVE Program (cve.org) e CISA ADP
7.2 CVSS 2.0 High 3.9 10.0 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-125 · Out-of-bounds Read

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed
Jun 27, 2022
Federal deadline
Jul 18, 2022
passed 1550 day(s) ago
Ransomware use
Known

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Metasploit modules
Exploit-DB
Proofs of concept on GitHub — 183 repositories; showing the 10 most starred

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 94.92%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
  • Hunt retroactively in logs from before Jun 27, 2022 (KEV listing): exploitation may have started earlier.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • Affected products added · polkit project/polkit, redhat/enterprise linux server update services for sap solutions, redhat/enterprise linux, redhat
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 7.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Added to CISA KEV (detected)
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Record created in this database
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • 2022
  • Added to CISA KEV catalog
    Jun 26, 2022 · CISA
  • CVE published
    Jan 28, 2022 · redhat

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

30 on the record

Elsewhere on this site

Canonical
every CVE for this vendor
2022-06
what else CISA listed that month
Memory corruption
same class
CWE-125
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-104046 Sssd: sssd: denial of service via incomplete identity provider authentication requests 9d
  • CVE-2026-104045 Sssd: sssd: denial of service via race condition in autofs responder 9d
  • CVE-2026-104047 Sssd: sssd: information disclosure via query injection in entra id lookups 9d
  • CVE-2026-104048 Sssd: sssd: authorization bypass via cross-domain username collision in hbac evaluation 9d
  • CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth 16d
  • CVE-2026-102555 Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding 16d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-4034 is "Red Hat Polkit Out-of-Bounds Read and Write Vulnerability", rated High. It affects Ubuntu Linux (Canonical); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 7.8 describes technical severity. EPSS 94.92% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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