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Unsigned processes could match a File Access Authorization exception intended for platform binaries

Moderate
mlw published GHSA-m4g5-c6w9-jv3f Aug 4, 2026

Software

santa

Affected versions

<= 2026.6

Patched versions

2026.7

Description

Summary

File Access Authorization lets an administrator restrict access to a path to a named set of processes. One selector, PlatformBinary, is meant to match only code shipped and signed by Apple as part of macOS.

Santa evaluated that check only for processes carrying a code signature. An unsigned process skipped it entirely and could satisfy an allow entry naming PlatformBinary as its only requirement, gaining access the administrator had reserved for Apple code.

The check had been grouped with the selectors that describe a code signature, which are correctly rejected for unsigned code. Whether the operating system considers an executable part of the platform is a meaningful question for unsigned code too, and the answer is simply no.

Impact

An unsigned local process could read data protected by an affected rule. The defect does not grant permissions the operating system would otherwise deny, and it is not an execution-policy bypass. An attacker still needs to get their unsigned process running, and still needs ordinary OS access to the target.

Affected configurations

A rule is affected when all of the following hold:

  • The rule is enforced rather than audit-only, and protects a path the attacker can reach.
  • One of its process entries names PlatformBinary as its only effective selector.
  • The attacker can run an unsigned process that already has OS-level permission for the target.

Selectors within a single process entry are conjunctive, so an entry that also specifies a Signing ID, Team ID, CDHash, certificate hash, or binary path is not affected. Separate process entries are independent alternatives, so an unaffected entry sitting alongside an affected one does not repair it.

The older TeamID=platform spelling is normalized to the same thing internally, so an entry written that way has the same exposure as one written with PlatformBinary.

Platform-binary-only entries were already a weak boundary

Platform binaries include the shells and general-purpose file utilities that ship with macOS. An allow entry naming only PlatformBinary therefore already permits /bin/sh, /bin/cat, and similar tools by design. Anyone with terminal access on the host could read the protected data through one of those permitted processes without relying on this defect at all.

The predicate should behave as documented, and the fix makes it do so. Even so, an entry that relies on PlatformBinary as its only selector does not provide a meaningful boundary in either direction. Treat this fix as closing a correctness gap rather than as making such a policy sound.

What changes in 2026.7

A PlatformBinary requirement now rejects every process the operating system does not report as a platform binary, unsigned processes included.

Expect access that was previously permitted to start being denied. If a workflow depended on an unsigned process reaching a path through such an entry, that entry needs a selector naming the process explicitly rather than relying on PlatformBinary.

Affected versions

Field Value
Affected Santa <= 2026.6
Fixed in Santa 2026.7
Severity Medium, CVSS v4.0 base score 4.8
CVSS CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CWE CWE-863: Incorrect Authorization

Mitigation

Upgrade to Santa 2026.7 or later.

Administrators can also remove the exposure through configuration, and doing so is worthwhile independent of this fix:

  • Review File Access Policy entries for any process entry whose only selector is PlatformBinary, including entries written as TeamID=platform.
  • Narrow those entries with an additional selector such as a Signing ID or a binary path, so the exception names the specific Apple tooling intended rather than all platform code. This closes the defect on affected versions and produces a tighter policy on fixed ones.

Credit

Reported by OpenAI Codex Security, Jamie Brim (@jamieb-oai).

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 Local
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality Low
Integrity Low
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:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

Credits