Cybersecurity professionals consider CVE-2026-100865 an immediate threat requiring urgent mitigation.
Status: Received on 27 Sep 2026, 02:17 UTC
Published on: 27 Sep 2026, 02:17 UTC
CVSS Release: version 3
disclosure@vulncheck.com
Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVE-2026-100865: Heym before 0.0.53 contains multiple independent vulnerabilities. (1) The workflow condition evaluator uses Python eval() without an effective sandbox, allowing any user who can edit a workflow branch/condition node — or who can import a workflow template containing a malicious condition node — to execute arbitrary Python code as the backend process user when the workflow runs. (2) Slack webhook signature verification and (3) Telegram webhook secret-token verification fail open when the trigger node has no credentialId or an empty signing secret, allowing anyone who knows the public webhook URL to trigger workflows with the owner's credentials without authentication. (4) The OAuth authorization endpoint does not validate the redirect_uri scheme, so an attacker who registers a public OAuth client with a javascript: or data: redirect_uri and lures a victim to the consent screen receives the authorization code and executes attacker-controlled JavaScript in the Heym origin, including access to the victim's HttpOnly auth cookie. (5) WorkflowExecutionToken, PortalSession, HITLRequest.public_token, and OAuthAuthorizationCode values are stored in plaintext, so any database read exposure yields valid scoped bearer tokens, including portal and HITL tokens with a 168-hour TTL that permit workflow execution on behalf of the owner.
The exploitability of CVE-2026-100865 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2026-100865 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-100865, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-100865, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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