CVE-2021-20227Public exploit

Read-after-free via premature HAVING rewrite

Published Mar 23, 2021 · Updated Aug 3, 2024

Use-after-free in SQLite before 3.34.1 allows local users who can run crafted SQL to trigger an internal read from freed memory. In havingToWhereExprCb() in src/select.c, a correlated WHERE term can be moved before a constant-false HAVING term during aggregate-subquery rewriting, leaving aggregate processing to read released memory. Arbitrary SQL execution is required; SQLite reports that no crash or code execution has been demonstrated and the condition is visible only under a memory sanitizer.

CVSS severity5.5
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in SQLite before 3.34.1 allows local users who can run crafted SQL to trigger an internal read from freed memory. In havingToWhereExprCb() in src/select.c, a correlated WHERE term can be moved before a constant-false HAVING term during aggregate-subquery rewriting, leaving aggregate processing to read released memory. Arbitrary SQL execution is required; SQLite reports that no crash or code execution has been demonstrated and the condition is visible only under a memory sanitizer.

The record

CVE
CVE-2021-20227
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
SQLite
Product
SQLite
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=sqlite 3.34.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

SQLite · SQLiteversion=sqlite 3.34.1

Published CVSS scores

2.1NVDAV:L/AC:L/Au:N/C:N/I:N/A:P
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5IBMCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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 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

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Your stack

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