CVE-2026-100531 in openclaw
Summary
by MITRE • 09/26/2026
The @openclaw/slack npm package before 2026.8.1 contains an authorization flaw in its Slack download-file handler: when a file lacks the share metadata used to prove it belongs to the requested conversation, the conversation-authorization check fails open. An authenticated caller restricted to a single conversation who knows or obtains a file identifier can therefore download file contents from outside that conversation's scope, disclosing data across configured conversation boundaries. The issue does not allow listing arbitrary Slack files and does not bypass Slack authentication itself. The issue is fixed in version 2026.8.1.
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Analysis
by VulDB Data Team • 09/26/2026
The vulnerability identified in the @openclaw/slack npm package prior to version 2026.8.1 represents a critical authorization flaw within its file download handling mechanism, specifically affecting how access control is enforced for Slack files. This issue stems from an improper implementation of security checks that are intended to restrict user actions to their authorized scope. In the context of enterprise communication platforms like Slack, applications often operate with permissions scoped to specific conversations or channels to ensure data isolation and privacy compliance. The flaw arises because the application relies on share metadata within a file object as the primary indicator for verifying whether the requesting user has permission to access that particular resource. When this metadata is absent, which can occur in various legitimate scenarios such as newly uploaded files or files shared via direct links without explicit conversation context, the authorization logic fails open rather than denying access by default.
From a technical perspective, this flaw constitutes an Insecure Direct Object Reference vulnerability where the application uses an untrusted input, specifically the file identifier provided by the client, to make security decisions based on incomplete data validation. The CWE classification for this issue is primarily aligned with CWE-284: Improper Access Control and potentially CWE-601: URL Redirection to Untrusted Site (if interpreted broadly as scope bypass) or more accurately CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes. The core failure lies in the assumption that share metadata is always present for files within a conversation, leading to a logic error where the absence of this attribute results in an implicit allow decision rather than a deny one. This violates the principle of least privilege and secure default configurations, allowing authenticated users to bypass intended boundaries.
The operational impact of this vulnerability allows an attacker who has valid authentication credentials restricted to a single conversation to escalate their access privileges laterally across other conversations within the same Slack workspace. By obtaining or guessing file identifiers from outside their authorized scope, the attacker can download sensitive documents, images, or data that were not intended for them. This leads to unauthorized disclosure of confidential information, potentially violating organizational security policies and regulatory compliance requirements such as GDPR or HIPAA if personal health information or personally identifiable information is involved. It is important to note that this vulnerability does not allow for arbitrary file listing nor does it bypass the underlying Slack authentication mechanisms; therefore, an attacker must already be authenticated and possess knowledge of specific file identifiers from other conversations to exploit this flaw effectively.
This type of access control violation maps directly to techniques observed in threat intelligence frameworks such as MITRE ATT&CK, specifically under T1078: Valid Accounts for initial access or persistence, combined with T1530: Data from Cloud Storage Object Discovery if the attacker were able to enumerate files, though here it is more accurately described by lateral movement within a trusted application context. The exploitation relies on the attacker's ability to identify file IDs belonging to other conversations, which may be achieved through social engineering or observing shared links in public channels before they are removed. To mitigate this risk, organizations using versions of @openclaw/slack prior to 2026.8.1 should immediately upgrade to version 2026.8.1 where the authorization logic has been corrected to enforce strict access controls regardless of metadata presence. Additionally, developers implementing similar integrations should ensure that all security checks default to deny and explicitly validate ownership or permission sets against a trusted source rather than relying on potentially missing optional attributes in API responses.