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SurrealDB CPU exhaustion via custom functions result in total DoS

High severity GitHub Reviewed Published Apr 10, 2025 in surrealdb/surrealdb • Updated Apr 11, 2025

Package

cargo surrealdb (Rust)

Affected versions

>= 2.2.0, < 2.2.2
>= 2.1.0, < 2.1.5
< 2.0.5

Patched versions

2.2.2
2.1.5
2.0.5

Description

SurrealDB allows authenticated users with OWNER or EDITOR permissions at the root, database or namespace levels to define their own database functions using the DEFINE FUNCTION statement

A custom database function comprises a name together with a function body. In the function body, the user programs the functionality of the function in terms of SurrealQL. The language includes a FOR keyword, used to implement for-loops.

Whilst the parser and interpreter constrain the number of iterations for a single for-loop, nesting several for-loops with a large number of iterations is possible. Thus, an attacker could define a function that comprises several nested for-loops with an iteration count of 1.000.000 each.

Executing the function will consume all the CPU time of the server, timeouts configured will not break the CPU consumption, and the function execution monopolizes all CPU time of the SurrealDB server, effectively preventing the server from executing functions, queries, commands of other users, or allowing further connections being established to the server.

Terminating the stuck server requires manual intervention which forces a quit on the server process, as the server application is not responsive any longer.

This issue was discovered and patched during an code audit and penetration test of SurrealDB by cure53, the severity defined within cure53's preliminary finding is high, matched by our CVSS v4 assessment.

Impact

Denial of Service vulnerability resulting in a stuck SurrealDB server requiring manual restart.

Patches

A patch has been introduced that adds a check in the ForEachStatement that checks if the context has been cancelled or timed out for every iteration.

  • Versions 2.0.5, 2.1.5, 2.2.2, and later are not affected by this issue.

Workarounds

For SurrealDB users that are unable to upgrade, consider setting the --allow-functions and/or --deny-functions options or corresponding SURREAL_CAPS_ALLOW_FUNC and/or SURREAL_CAPS_DENY_FUNC environment variables, documented within capabilities, to either block all custom functions, or only allow trusted functions to execute.

References

SurrealQL Documentation - DEFINE FUNCTION Statement
SurrealQL Documentation - FOR Statement
SurrealDB Documentation - Capabilities
SurrealDB Documentation - Environment variables
#5597

References

@rowan-baker rowan-baker published to surrealdb/surrealdb Apr 10, 2025
Published to the GitHub Advisory Database Apr 11, 2025
Reviewed Apr 11, 2025
Last updated Apr 11, 2025

Severity

High

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 Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability High
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:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS score

Weaknesses

CVE ID

No known CVE

GHSA ID

GHSA-pxw4-94j3-v9pf

Source code

Credits

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