CVE-2021-36087

Policy compiler crash via stale optional-block reference

Published Jul 1, 2021 · Updated Nov 3, 2025

Heap-based buffer over-read in the SELinux 3.2 CIL compiler allows local users to interrupt policy compilation with a crafted CIL policy. The compiler permits invalid declarations inside optional blocks, so disabling an optional can delete a block still referenced during later error handling. Exploitation requires privileges to write and compile a policy; the demonstrated consequence is a temporary compiler crash rather than system-wide loss of availability.

CVSS severity3.3
Low
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer over-read in the SELinux 3.2 CIL compiler allows local users to interrupt policy compilation with a crafted CIL policy. The compiler permits invalid declarations inside optional blocks, so disabling an optional can delete a block still referenced during later error handling. Exploitation requires privileges to write and compile a policy; the demonstrated consequence is a temporary compiler crash rather than system-wide loss of availability.

The record

CVE
CVE-2021-36087
Published
Jul 1, 2021
Updated
Nov 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, CWE-119, T1499.004
Attack vector
local
Privileges
authenticated

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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

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:L/UI:N/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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

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Your stack

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