CVE-2025-21605Network attack vector

Service exhaustion via unlimited unauthenticated output buffers

Published Apr 23, 2025 · Updated Feb 10, 2026

Resource exhaustion in Redis 2.6 through 7.4.2 allows remote attackers to interrupt the service through unauthenticated connections. Normal-client output buffers have no default size limit, so repeated NOAUTH replies accumulate without throttling until memory is exhausted. Network access to the Redis endpoint is sufficient even when password authentication is enabled; the bounded consequence is server termination or loss of service.

CVSS severity7.5
High
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Redis 2.6 through 7.4.2 allows remote attackers to interrupt the service through unauthenticated connections. Normal-client output buffers have no default size limit, so repeated NOAUTH replies accumulate without throttling until memory is exhausted. Network access to the Redis endpoint is sufficient even when password authentication is enabled; the bounded consequence is server termination or loss of service.

The record

CVE
CVE-2025-21605
Published
Apr 23, 2025
Updated
Feb 10, 2026
Vendor
Redis
Product
Redis
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 10, 2026Record 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=>= 2.6, < 7.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Redis · Redisversion=>= 2.6, < 7.4.3

Published CVSS scores

7.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

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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