CVE-2026-119664 in Tamery
Summary
by MITRE • 10/30/2026
Tamery (formerly Conar) 0.26.1 before 0.99.0 contains an authorization bypass vulnerability in the cloud sync API chatsMessages.update handler, which leaves the client-supplied chatId writable. Authenticated Pro subscribers who know another user's chat ID can move messages with arbitrary parts and metadata into the victim's AI chat history.
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Analysis
by VulDB Data Team • 10/30/2026
The identified security flaw resides within Tamery version 0.26.1 through versions prior to 0.99.0, specifically affecting the cloud synchronization API endpoint responsible for updating chat messages. This vulnerability constitutes a critical authorization bypass that undermines the fundamental principle of access control by allowing authenticated users to manipulate resources belonging to other users. The core technical deficiency lies in the chatsMessages.update handler, which fails to adequately validate whether the requesting user possesses legitimate ownership or administrative privileges over the specific chat identifier provided in the request payload. Consequently, the system accepts and processes client-supplied chatId values without verifying that this ID corresponds to a conversation owned by the authenticated session initiating the update operation. This lack of server-side authorization checks creates an insecure direct object reference scenario where the application trusts user input regarding resource identity rather than enforcing strict access policies based on the current user context.
From an operational perspective, this vulnerability enables significant data integrity and privacy violations for users subscribed to the Pro tier. An attacker who has obtained valid authentication credentials can exploit this flaw by crafting malicious API requests that target arbitrary chat identifiers belonging to other victims. By supplying a victim's unique chat ID in place of their own, the attacker gains the ability to inject, modify, or delete messages within the victim's AI chat history. This capability allows for the insertion of arbitrary content and metadata into conversations where the user expects privacy and data isolation from external interference. The impact extends beyond simple message manipulation; it compromises the trustworthiness of the AI-generated responses derived from these chats, potentially leading to misinformation or malicious instruction injection if the attacker inserts deceptive prompts that influence subsequent AI behavior within the victim's session.
This vulnerability aligns with Common Weakness Enumeration CWE-284, which describes Improper Access Control, as well as CWE-601, URL Redirection to Untrusted Site (Open Redirect) in a broader sense of object reference manipulation, though it is most accurately classified under CWE-862: Missing Authorization. In the context of the MITRE ATT&CK framework for enterprise security, this behavior maps directly to Tactic TA0005: Defense Evasion and specifically Technique T1534: Internal Spearphishing if used to deceive users via chat history manipulation, or more accurately to data exfiltration and tampering techniques under Data Manipulation. The ability to write arbitrary metadata suggests potential for further exploitation vectors such as prompt injection attacks that could compromise the AI model's safety guardrails when processing the corrupted conversation history.
Mitigation strategies must prioritize immediate patching of all affected instances to version 0.99.0 or later, where this authorization logic has been corrected. For organizations unable to upgrade immediately, implementing a strict server-side validation layer is essential. This involves ensuring that every API request for chat modification includes a verification step that cross-references the provided chatId against an access control list associated with the authenticated user's account ID. Additionally, adopting principle of least privilege in API design requires that endpoints only accept identifiers generated by the system itself rather than those supplied directly by clients without validation. Security monitoring should also be enhanced to detect anomalous patterns where a single authentication token is used to update chat IDs not previously accessed by that session, which may indicate active exploitation attempts.