CVE-2021-32761Network attack vector

Heap corruption via BITFIELD integer overflow

Published Jul 21, 2021 · Updated Aug 3, 2024

Integer overflow in Redis 2.2 and later before fixed releases allows remote authenticated users to corrupt heap memory via crafted BITFIELD commands. The BITFIELD implementation on 32-bit builds overflows bit offsets after an attacker raises proto-max-bulk-len and submits specially crafted requests, causing out-of-bounds access and buffer overflow. Exploitation requires Redis command access and a 32-bit executable; consequences include heap disclosure, corruption, or possible remote code execution, while 64-bit builds are not affected.

CVSS severity7.5
High
EPSS probability37.63%
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 Redis 2.2 and later before fixed releases allows remote authenticated users to corrupt heap memory via crafted BITFIELD commands. The BITFIELD implementation on 32-bit builds overflows bit offsets after an attacker raises proto-max-bulk-len and submits specially crafted requests, causing out-of-bounds access and buffer overflow. Exploitation requires Redis command access and a 32-bit executable; consequences include heap disclosure, corruption, or possible remote code execution, while 64-bit builds are not affected.

The record

CVE
CVE-2021-32761
Published
Jul 21, 2021
Updated
Aug 3, 2024
Vendor
Redis
Product
Redis
Classifications
CWE-125, CWE-680, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 21, 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=>= 2.2, < 5.0.13
  2. Affected versionversion=>= 6.0.0, < 6.0.15
  3. Affected versionversion=>= 6.2.0, < 6.2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Redis · Redisversion=>= 2.2, < 5.0.13; version=>= 6.0.0, < 6.0.15; version=>= 6.2.0, < 6.2.5

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:H/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-125Out-of-bounds Read
CWE-680Integer Overflow to Buffer Overflow
T1210Exploitation of Remote Services

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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