CVE-2021-36084Public exploit

Compiler crash via retained freed class-permission list

Published Jul 1, 2021 · Updated Nov 3, 2025

Use-after-free in the SELinux 3.2 CIL compiler allows local users to crash policy compilation through crafted CIL policy input. When an optional block is reset, cil_reset_classpermission retains a classperms list whose referenced entries can be freed, and later verification dereferences those entries. Exploitation requires user interaction to compile attacker-controlled CIL; the demonstrated consequence is a compiler crash.

CVSS severity3.3
Low
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in the SELinux 3.2 CIL compiler allows local users to crash policy compilation through crafted CIL policy input. When an optional block is reset, cil_reset_classpermission retains a classperms list whose referenced entries can be freed, and later verification dereferences those entries. Exploitation requires user interaction to compile attacker-controlled CIL; the demonstrated consequence is a compiler crash.

The record

CVE
CVE-2021-36084
Published
Jul 1, 2021
Updated
Nov 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo