CVE-2026-101050

Executive Summary

CVE-2026-101050 is an authentication bypass vulnerability in the Heym workflow automation platform affecting versions before 0.0.53. The flaw allows remote, unauthenticated attackers to bypass Telegram webhook authentication when the credential_id parameter is absent or the secret_token is empty, enabling forged update injection. Successful exploitation permits attackers to trigger workflows using the owner's configured credentials, potentially executing arbitrary actions on attacker-controlled input, resulting in high integrity impact (I:H) and limited confidentiality impact (C:L).

Technical Analysis

The vulnerability resides in Heym's Telegram webhook endpoint authentication mechanism. Telegram provides a security feature where bots can register a secret token during webhook setup; this token is then transmitted in the X-Telegram-Bot-Api-Secret-Token HTTP header with every update request. Legitimate webhook handlers must validate this header against the locally configured secret to ensure the request originated from Telegram's infrastructure.

In Heym versions prior to 0.0.53, the verification logic fails when the credential_id parameter is missing or when the configured secret_token is empty. Under these conditions, the webhook endpoint processes incoming POST requests without validating the X-Telegram-Bot-Api-Secret-Token header. This constitutes an improper authentication vulnerability (CWE-287), specifically a missing authentication check for a critical function.

The attack surface is the publicly exposed Telegram webhook endpoint. Any Heym instance with a Telegram integration configured—and where the secret_token was not set or credential_id was omitted—is vulnerable. The AC:H (Attack Complexity: High) rating in the CVSS vector reflects that exploitation requires specific preconditions: the target must have a Telegram webhook configured with a missing or empty secret token, and the attacker must identify a valid webhook path. However, these conditions are common in misconfigured or default deployments, and once met, no authentication is required (PR:N).

The CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N) yields a base score of 6.5 (Medium severity). The high integrity impact (I:H) stems from the ability to trigger workflows with the owner's credentials, potentially causing unauthorized actions, data manipulation, or downstream system changes. The limited confidentiality impact (C:L) suggests some information disclosure may occur through workflow execution, though the primary risk is unauthorized action execution.

The vulnerability does not provide a direct code execution primitive but rather abuses the workflow engine's trust in webhook-originated events. Heym, as a workflow automation platform (similar in concept to n8n, Zapier, or Make), connects various services and executes actions based on triggers. A forged Telegram update can initiate any workflow that listens on the affected bot's webhook, with all subsequent nodes executing under the owner's configured credentials—API keys, OAuth tokens, database connections, and other secrets stored within the platform.

No public proof-of-concept, exploit code, or Nuclei template is currently available. The patch confidence is 0/4, indicating no patch evidence from any tracked source, though the NVD description references version 0.0.53 as the fixed release. No affected version ranges are published in OSV, and the vendor has not released a formal advisory per available data.

Exploitation Scenarios

No public PoC is available; the following attack chain is inferred from the vulnerability class and the NVD description.

1) Reconnaissance and Target Identification: An attacker identifies internet-facing Heym instances by scanning for the platform's web interface or known webhook URL patterns. Shodan queries such as http.title:"Heym" or http.html:"telegram" can help enumerate exposed instances. The attacker must determine whether a Telegram webhook is configured and whether the credential_id is absent or secret_token is empty. This may be inferred through error responses, timing differences, or by observing that the endpoint accepts requests without the X-Telegram-Bot-Api-Secret-Token header.

2) Triggering the Flaw: The attacker crafts a POST request to the Heym Telegram webhook endpoint, mimicking the structure of a legitimate Telegram update. Because the authentication check is skipped when credential_id is absent or secret_token is empty, the request is accepted without a valid X-Telegram-Bot-Api-Secret-Token header. The attacker does not need to know the bot token or any secret; they only need the webhook URL path.

3) Payload and Execution: The forged update contains attacker-controlled data within fields that the workflow uses as input. When Heym processes the update, it triggers the associated workflow. All nodes in that workflow execute using the owner's stored credentials. The attacker can influence the workflow's behavior through the crafted update payload—for example, by supplying a malicious message text, user ID, or file reference that the workflow acts upon. The specific impact depends on the workflow's logic (e.g., sending messages, modifying data in connected services, executing HTTP requests to external systems).

4) Post-Exploitation Impact: Successful exploitation allows the attacker to perform actions via the workflow with the owner's privileges. This could include exfiltrating data from connected services, sending unauthorized messages, creating or modifying records, or triggering further workflows. The high integrity impact reflects the attacker's ability to manipulate systems and data through the trusted workflow execution context. Limited confidentiality impact suggests some data may be disclosed in responses or side effects. The scope remains unchanged (S:U), meaning the vulnerable component and affected resources are within the same security authority.

Impact Assessment

The business impact of CVE-2026-101050 is significant for organizations relying on Heym for workflow automation with Telegram integrations. An attacker can inject forged updates to trigger arbitrary workflows, leading to unauthorized actions performed with the victim's credentials. This can result in data corruption, unauthorized data modification, service disruption, or lateral movement into connected systems. The CVSS score of 6.5 (Medium) reflects the high attack complexity (preconditions required) but high integrity impact once exploited.

Affected systems are Heym instances running versions before 0.0.53 that have Telegram webhook integrations configured without a secret token or with a missing credential_id. The blast radius extends to all downstream services, APIs, and data stores that the workflow interacts with using the owner's credentials. No CISA KEV status indicates no known active exploitation in the wild at this time, but the lack of a public PoC does not eliminate risk. The EPSS score is not yet available.

Detection Guidance

Sigma Rule

title: Heym Telegram Webhook Authentication Bypass
id: 5f8c3a2e-1b7d-4c9a-8e2f-3d6a7b9c0e1f
status: experimental
description: Detects POST requests to Heym Telegram webhook endpoints missing the X-Telegram-Bot-Api-Secret-Token header or containing suspicious update payloads.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-101050
author: Threat Intelligence
date: 2026/01/15
tags:
  - attack.t1190
  - attack.initial_access
logsource:
  category: webserver
  product: heym
detection:
  selection:
    http.method: 'POST'
    http.url|contains: '/webhook'
    http.url|contains: 'telegram'
  filter_legit:
    http.request.headers.X-Telegram-Bot-Api-Secret-Token|exists: true
  condition: selection and not filter_legit
falsepositives:
  - Legitimate webhook configurations where secret token is intentionally omitted (misconfiguration)
level: high

YARA Rule

rule CVE_2026_101050_Heym_Telegram_Bypass
{
    meta:
        description = "Detects Heym webhook handler code lacking X-Telegram-Bot-Api-Secret-Token validation"
        author = "Threat Intelligence"
        date = "2026-01-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-101050"
        severity = "high"
    strings:
        $s1 = "X-Telegram-Bot-Api-Secret-Token" ascii wide
        $s2 = "credential_id" ascii wide
        $s3 = "secret_token" ascii wide
        $s4 = "telegram" ascii wide nocase
    condition:
        uint16(0) == 0x5A4D or uint32(0) == 0x464C457F or true
        and 2 of ($s1, $s2, $s3, $s4)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-101050 Heym Telegram Webhook Auth Bypass Attempt"; flow:to_server,established; http.method; content:"POST"; http.uri; content:"webhook"; http.uri; content:"telegram"; http.header; content:!"X-Telegram-Bot-Api-Secret-Token"; classtype:attempted-admin; sid:2026101050; rev:1; metadata:created_at 2026_01_15, cve CVE-2026-101050;)

Elastic Detection

network where http.request.method == "POST" and
  stringContains(http.request.url.path, "webhook") and
  stringContains(http.request.url.path, "telegram") and
  not stringContains(http.request.headers, "X-Telegram-Bot-Api-Secret-Token")

Splunk SPL Query

index=web OR index=proxy
method=POST
(uri_path="*webhook*" OR uri_path="*telegram*")
NOT (http_request_headers="*X-Telegram-Bot-Api-Secret-Token*")
| stats count by src_ip, uri_path, user_agent
| where count > 1
| sort - count

Wazuh OSSEC Rule

<group name="heym,web,">
  <rule id="20261050" level="12">
    <decoded_as>json</decoded_as>
    <field name="http.method">POST</field>
    <field name="http.url" type="pcre2">(?i)(webhook|telegram)</field>
    <field name="http.request.headers.X-Telegram-Bot-Api-Secret-Token" negate="yes">.*</field>
    <description>CVE-2026-101050: Heym Telegram webhook request without secret token header</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack.initial_access,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1) Immediate Mitigations:

• Configure a non-empty secret_token for all Telegram webhook integrations in Heym. This ensures the X-Telegram-Bot-Api-Secret-Token header is validated.
• Ensure the credential_id parameter is always present in webhook configurations.
• If a secret token cannot be set, restrict network access to the Heym webhook endpoint using firewall rules, allowing only Telegram's published IP ranges (149.154.160.0/20 and 91.108.4.0/22).
• Disable or remove Telegram webhook integrations that are not actively used.
• Monitor Heym instances for anomalous workflow executions triggered by webhook events.

2) Patch/Upgrade Steps:

• Upgrade Heym to version 0.0.53 or later as referenced in the NVD description. Verify the fix by confirming that webhook requests without a valid X-Telegram-Bot-Api-Secret-Token header are rejected.
• Since no patch evidence is available from tracked sources, validate the upgrade path through the vendor's official repository or release notes before deployment.
• If upgrading is not immediately possible, apply the immediate mitigations above as compensating controls.

3) Long-Term Hardening:

• Implement a mandatory authentication check for all webhook endpoints, regardless of whether a secret token is configured. Fail closed—reject requests if the secret token is missing or empty.
• Adopt a secure-by-default configuration where webhook secrets are required and auto-generated during setup.
• Regularly audit workflow configurations for missing or empty security parameters.
• Employ network segmentation to limit the blast radius of compromised workflow credentials.
• Integrate webhook authentication logs into SIEM for continuous monitoring and alerting on bypass attempts.

References

1. NVD — CVE-2026-101050: https://nvd.nist.gov/vuln/detail/CVE-2026-101050
2. Telegram Bot API — setWebhook secret_token documentation: https://core.telegram.org/bots/api#setwebhook
3. CWE-287: Improper Authentication: https://cwe.mitre.org/data/definitions/287.html
4. CISA KEV Catalog: Not applicable — no known exploitation in the wild.
5. Heym project repository (for version 0.0.53 release verification): No advisory available at time of writing.