CVE-2021-41099Network attack vector

Code execution via overflowed SDS buffer growth

Published Oct 4, 2021 · Updated Aug 4, 2024

Integer overflow in Redis before 5.0.14 and in 6.0.0 through 6.0.15 or 6.2.0 through 6.2.5 allows remote authenticated users to corrupt the heap. The sdsMakeRoomFor function doubles a requested SDS allocation length but checked header overhead against the old string length, allowing size_t wraparound and an undersized heap allocation. Exploitation requires permission to raise proto-max-bulk-len and crafted network payloads or commands, resulting in a server crash or code execution in the Redis process.

CVSS severity7.5
High
EPSS probability3.68%
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 before 5.0.14 and in 6.0.0 through 6.0.15 or 6.2.0 through 6.2.5 allows remote authenticated users to corrupt the heap. The sdsMakeRoomFor function doubles a requested SDS allocation length but checked header overhead against the old string length, allowing size_t wraparound and an undersized heap allocation. Exploitation requires permission to raise proto-max-bulk-len and crafted network payloads or commands, resulting in a server crash or code execution in the Redis process.

The record

CVE
CVE-2021-41099
Published
Oct 4, 2021
Updated
Aug 4, 2024
Vendor
Redis
Product
Redis
Classifications
CWE-680, CWE-190, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=< 5.0.14
  2. Affected versionversion=>= 6.0.0, < 6.0.16
  3. Affected versionversion=>= 6.2.0, 6.2.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Redis · Redisversion=< 5.0.14; version=>= 6.0.0, < 6.0.16; version=>= 6.2.0, 6.2.6

Published CVSS scores

6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
7.5GitHub, Inc.CVSS: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-680Integer Overflow to Buffer Overflow
CWE-190Integer Overflow or Wraparound
T1190Exploit Public-Facing Application

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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