CVE-2021-32765Network attack vector

Memory corruption via overflowing reply-array allocation

Published Oct 4, 2021 · Updated Aug 3, 2024

Integer overflow in the Hiredis reply parser before 1.0.1 allows attackers to corrupt memory via a crafted RESP multi-bulk reply. createArrayObject multiplies the untrusted element count by the pointer size for calloc without first rejecting values that exceed SIZE_MAX. The client must parse attacker-controlled or corrupted RESP data, and the default element limit leaves 64-bit builds likely unaffected.

CVSS severity8.8
High
EPSS probability2.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the Hiredis reply parser before 1.0.1 allows attackers to corrupt memory via a crafted RESP multi-bulk reply. createArrayObject multiplies the untrusted element count by the pointer size for calloc without first rejecting values that exceed SIZE_MAX. The client must parse attacker-controlled or corrupted RESP data, and the default element limit leaves 64-bit builds likely unaffected.

The record

CVE
CVE-2021-32765
Published
Oct 4, 2021
Updated
Aug 3, 2024
Vendor
Redis
Product
Hiredis
Classifications
CWE-190, CWE-680, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 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=< 1.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Redis · Hiredisversion=< 1.0.1

Published CVSS scores

6.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
CWE-680Integer Overflow to Buffer Overflow
T1203Exploitation for Client Execution

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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