CVE-2026-82282 in Atlantis
Summary
by MITRE • 08/28/2026
Atlantis through 0.47.1 fails to authenticate the /github-app/setup endpoint, allowing unauthenticated attackers to access GitHub App credentials. Attackers can observe or intercept the GitHub redirect during setup to obtain the RSA private key and webhook secret, enabling installation token minting and webhook payload forgery.
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Analysis
by VulDB Data Team • 08/29/2026
The vulnerability identified in Atlantis versions through 0.47.1 represents a critical authentication bypass within the application's integration with GitHub Apps. Specifically, the endpoint designated for initiating the GitHub App setup process lacks proper access control mechanisms. This architectural flaw allows unauthenticated actors to interact directly with the /github-app/setup route without providing valid credentials or session tokens. In a secure implementation of OAuth 2.0 flows typical for GitHub integrations, such endpoints must enforce strict authentication checks to ensure that only authorized administrators can initiate the configuration process. The absence of this check fundamentally undermines the security boundary intended to protect sensitive integration secrets during their generation and exchange phases.
The technical consequence of this misconfiguration is severe because it exposes high-value cryptographic material and secret keys to potential interception or observation. During the GitHub App setup flow, an RSA private key and a webhook signing secret are generated and exchanged between Atlantis and the GitHub platform. Because the initial request can be made by any actor on the network path or with access to the application interface without authentication, attackers can trigger this process and observe the resulting redirect responses. By analyzing these redirects, malicious actors can extract the RSA private key required for authenticating API requests as the app itself, along with the webhook secret used to verify the integrity of incoming events from GitHub.
The operational impact of obtaining these credentials is extensive, granting an attacker full control over the Atlantis instance's integration capabilities. With the minted installation token derived from the stolen RSA key, an adversary can impersonate the GitHub App and execute arbitrary operations within the associated repositories or organizations. This includes reading sensitive codebases, modifying pull requests, triggering CI/CD pipelines with malicious payloads, and potentially escalating privileges to compromise downstream systems connected via these automated workflows. Furthermore, possession of the webhook secret allows for payload forgery, enabling attackers to send spoofed events that could trigger unintended actions within the deployment pipeline or exfiltrate data under the guise of legitimate system activity.
This vulnerability aligns with CWE-287, which describes Improper Authentication, as well as CWE-359 regarding Exposure of Private Information in URLs and redirects. From a threat modeling perspective using MITRE ATT&CK techniques, this flaw facilitates Initial Access through T1078 Valid Accounts if the attacker uses the forged app identity, and potentially Credential Access via interception of sensitive configuration data. It also supports Supply Chain Compromise scenarios by allowing manipulation of automated build and deployment processes.
Mitigation strategies must prioritize immediate patching to version 0.48 or later where this authentication check has been implemented correctly. In environments where upgrading is not immediately feasible, network-level controls such as IP whitelisting for the Atlantis service endpoints can provide a temporary layer of defense by restricting access to trusted internal networks only. Additionally, organizations should audit their GitHub App configurations and rotate any RSA keys and webhook secrets that may have been exposed during the window of vulnerability. Implementing strict monitoring on webhook delivery logs and API usage patterns associated with affected app installations will aid in detecting potential exploitation attempts post-patch deployment.