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Protocol State Desynchronization in Lettuce Redis Client Following Fatal JVM Errors

Low
uglide published GHSA-5gww-fr9x-3pv7 Feb 3, 2026

Package

lettuce-core (io.lettuce)

Affected versions

7.2.0
7.1.0
7.0.0
< 6.8.2

Patched versions

7.2.1
7.1.1
7.0.1
6.8.2

Description

Impact

A protocol state desynchronization issue has been reported in the Lettuce Java Redis client. Under certain error conditions—specifically when a fatal java.lang.Error (such as OutOfMemoryError) occurs during command processing—the Lettuce event loop may continue operating in an inconsistent internal state. As a result, Redis responses may become misaligned with their originating requests, leading to deserialization failures (for example, UnsupportedOperationException: io.lettuce.core.output.ValueOutput does not support set(long)) and potentially leaking sensitive information from one application session to another.

This issue impacts applications using the Lettuce client (io.lettuce:lettuce-core) across synchronous, asynchronous, and reactive APIs, particularly those that rely on long-lived connections and do not fully reset client state after fatal JVM errors.

Patches

The issue was resolved and backported to the following versions:
https://github.com/redis/lettuce/releases/tag/6.8.2.RELEASE
https://github.com/redis/lettuce/releases/tag/7.0.1.RELEASE
https://github.com/redis/lettuce/releases/tag/7.1.1.RELEASE
https://github.com/redis/lettuce/releases/tag/7.2.1.RELEASE

Workarounds

We strongly recommend upgrading Lettuce client to the patched versions. In cases when upgrade is not possible, users may mitigate the impact through the following measures:

  • Force connection termination on fatal errors: Ensure that any java.lang.Error encountered in the application lifecycle triggers a full shutdown and recreation of the Lettuce RedisClient and its connections.
  • Reduce likelihood of fatal JVM errors: Tune JVM memory settings, garbage collection, and workload characteristics to minimize the risk of OutOfMemoryError and similar fatal conditions.
  • Limit connection reuse in high-risk workloads: Avoid sharing a single long-lived connection across workloads where fatal errors are more likely to occur.

These mitigations do not eliminate the underlying issue but can reduce the risk of incorrect behavior following a fatal error.

Credits

Special thanks to the Rapid7 researchers for this discovering and reporting this vulnarability:

Ryan Williams, Distinguished Software Engineer, Rapid7

Allen Hadden, Senior Principal Engineer, Rapid7

Erez Breiman, Distinguished Software Engineer, Rapid7

References

#3132
https://github.com/nordnet/lettuce-out-of-order

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Local
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality Low
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

No CWEs