Predis is a flexible and feature-complete Redis and Valkey client for PHP. From version 3.0.0-RC1 until version 3.3.0, pipeline handling on aggregate cluster and replication connections reparses an already serialized RESP buffer in AbstractAggregateConnection::write() by splitting it with explode("\r\n") instead of honoring RESP length prefixes. Attacker-controlled keys or values containing CRLF sequences can therefore be interpreted by Command::deserializeCommand() as additional commands. On cluster connections, ClusterStrategy::getFakeKey() can route injected keyless commands using the literal fake key value "key", permitting operations such as shard-wide cache deletion, targeted data modification, data reads, or node disruption. On replication connections, malformed reparsing can throw an uncaught exception and repeatedly terminate affected requests. Only pipeline() reaches this vulnerable path; transaction() and MULTI are not affected. This issue is fixed in version 3.3.0.

Affected: Packagist: predis/predis

### Summary

An improper CRLF neutralization flaw in Predis' pipeline handling on aggregate connections lets an unauthenticated attacker who can influence any pipelined argument — a value **or** a key, e.g. a URL slug used as a cache key — smuggle arbitrary Redis commands into the connection.

- On **cluster** connections (`cluster` option, incl. client-side sharding) this is remote command injection: shard-wide `FLUSHDB`, targeted `DEL`/`SET`, same-slot key theft via `GET`, cache poisoning, and possible node/cluster outage. - On **replication** connections (`replication` option) it is a reliable, repeatable denial of service (uncaught fatal error) triggered by any value containing `\r\n`.

### Details

When a pipeline is executed over an aggregate connection, `AbstractAggregateConnection::write()` re-parses the already-serialized pipeline buffer with `explode("\r\n")` instead of honoring RESP length prefixes:

- https://github.com/predis/predis/blob/v3.2.0/src/Connection/AbstractAggregateConnection.php#L78-L94 - splits the buffer on `\r\n`, ignoring `$<len>` bulk lengths, - rebuilds each chunk via `Command::deserializeCommand()` (https://github.com/predis/predis/blob/v3.2.0/src/Command/Command.php#L157) to decide routing, - writes each chunk to the connection chosen for that (fake) command.

RESP is length-prefixed, so the Redis **server** parses the original stream correctly — but this second, client-side parser treats attacker-controlled `\r\n` seq…

Affected: Ubuntu:16.04:LTS: php-nrk-predis, Ubuntu:18.04:LTS: php-nrk-predis, Ubuntu:20.04:LTS: php-nrk-predis, Ubuntu:22.04:LTS: php-nrk-predis, Ubuntu:24.04:LTS: php-nrk-predis, Ubuntu:26.04:LTS: php-nrk-predis

Predis is a flexible and feature-complete Redis and Valkey client for PHP. From version 3.0.0-RC1 until version 3.3.0, pipeline handling on aggregate cluster and replication connections reparses an already serialized RESP buffer in AbstractAggregateConnection::write() by splitting it with explode("\r\n") instead of honoring RESP length prefixes. Attacker-controlled keys or values containing CRLF sequences can therefore be interpreted by Command::deserializeCommand() as additional commands. On cluster connections, ClusterStrategy::getFakeKey() can route injected keyless commands using the literal fake key value "key", permitting operations such as shard-wide cache deletion, targeted data modification, data reads, or node disruption. On replication connections, malformed reparsing can throw an uncaught exception and repeatedly terminate affected requests. Only pipeline() reaches this vulnerable path; transaction() and MULTI are not affected. This issue is fixed in version 3.3.0.