CVE-2025-21605
highpriority · track · 0EPSS 0.009 · 59 %ileDEEURUUSEPSS · scored 2026-10-27
Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.9–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (59)
Products and version ranges known to be affected.
advisories (4)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2025-0877Redis: Schwachstelle ermöglicht Denial of ServiceDeutsch2025-04-23csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Redis ausnutzen, um einen Denial of Service Angriff durchzuführen.
- BIT-keydb-2025-21605Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client2025-04-25vendor · osvUS
Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.
- BIT-redis-2025-21605Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client2025-04-25vendor · osvUS
Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.
- BIT-valkey-2025-21605Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client2025-04-25vendor · osvUS
Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.
also known as (7)
Other names and identifiers for this entity.
- CNNVD-202504-3445cnnvd
- EUVD-2025-12407enisa_euvd
- BDU:2025-05997fstec_bdu
- BIT-keydb-2025-21605osv
- BIT-redis-2025-21605osv
- BIT-valkey-2025-21605osv
- GHSA-r67f-p999-2gffosv
sources
Which sources assert this record, and when.
references (13)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2025-21605cnnvd
- https://github.com/redis/redis/releases/tag/7.4.3cnnvd
- https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gffcnnvd
- https://redis.io/downloads/#stackPatchcnnvd
- https://vigilance.fr/vulnerability/Redis-overload-via-Output-Buffers-Unlimited-Growth-46940cnnvd
- https://github.com/redis/redis/releases/tag/7.4.3enisa_euvd
- https://github.com/redis/redis/security/advisories/GHSA-r67f-p999-2gffenisa_euvd
- https://github.com/redis/redis/releases/tag/7.4.3Release Notesnvd
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