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SymfonyRuntime CVE-2024-50340 Patch Bypass: Web Requests Can Still Set APP_ENV/APP_DEBUG via parse_str/SAPI Argv Mismatch

Moderate severity GitHub Reviewed Published May 20, 2026 in symfony/symfony • Updated Jun 9, 2026

Package

composer symfony/runtime (Composer)

Affected versions

>= 5.4.46, < 5.4.52
>= 6.4.14, < 6.4.40
>= 7.1.7, < 7.4.12
>= 8.0.0, < 8.0.12

Patched versions

5.4.52
6.4.40
7.4.12
8.0.12
composer symfony/symfony (Composer)
>= 5.4.46, < 5.4.52
>= 6.4.14, < 6.4.40
>= 7.1.7, < 7.4.12
>= 8.0.0, < 8.0.12
5.4.52
6.4.40
7.4.12
8.0.12

Description

Description

CVE-2024-50340 (GHSA-x8vp-gf4q-mw5j) addressed an issue where, with register_argc_argv=On, a crafted query string let an unauthenticated GET change the kernel environment and debug flag by feeding --env/--no-debug through $_SERVER['argv']. The fix shipped in symfony/runtime 5.4.46 / 6.4.14 / 7.1.7 gated the argv read on empty($_GET) as a proxy for "is this a CLI invocation".

That proxy is unsafe: parse_str() (which builds $_GET) and the web SAPI (which builds $_SERVER['argv'] from the raw query when register_argc_argv=On) do not agree on every input, so an attacker can craft a query that leaves $_GET empty while $_SERVER['argv'] carries the attacker's flags. SymfonyRuntime::getInput() then parses them, restoring the exact primitive CVE-2024-50340 was meant to prevent.

Preconditions and impact match the original CVE: web SAPI, register_argc_argv=On, app booted through symfony/runtime; from an unauthenticated GET an attacker can flip APP_ENV and toggle APP_DEBUG.

Resolution

SymfonyRuntime now gates the argv read on isset($_SERVER['QUERY_STRING']) rather than on empty($_GET). QUERY_STRING is the same input the SAPI uses to build argv, so the security check and the thing it protects no longer parse different sources. Worker SAPIs (FrankenPHP / RoadRunner / Swoole) keep working because the runtime constructor runs once at boot when QUERY_STRING is unset.

The patch for this issue is available here for branch 5.4.

Credits

SymfonyRuntime would like to thank 0xEr3n for reporting the issue and Nicolas Grekas for providing the fix.

References

@nicolas-grekas nicolas-grekas published to symfony/symfony May 20, 2026
Published to the GitHub Advisory Database Jun 9, 2026
Reviewed Jun 9, 2026
Last updated Jun 9, 2026

Severity

Moderate

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 None
User interaction None
Vulnerable System Impact Metrics
Confidentiality Low
Integrity Low
Availability Low
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:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(27th percentile)

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Learn more on MITRE.

Interpretation Conflict

Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. Learn more on MITRE.

CVE ID

CVE-2026-47767

GHSA ID

GHSA-fqc7-9xjw-jrh3

Source code

Credits

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