Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client
Summary
Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client
Original description
The description as published by the source.
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.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Alpine Linux ALPINE-CVE-2025-21605 redis Fixed in: 6.2.18-r0
- Debian DEBIAN-CVE-2025-21605 redict Fixed in: 7.3.5+ds-1
- Ubuntu UBUNTU-CVE-2025-21605 redis
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- web github.com
- web lists.debian.org
- web github.com
- web vicarius.io
- web vicarius.io