CVE Catalog

CVE-2026-72861

MediumCVSS 5.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

In the github-issue-bot templates in appwrite/templates, the GitHub webhook signature verification is inverted. When the X-Hub-Signature-256 header is absent, the verifyWebhook function returns success without HMAC verification, allowing unauthenticated requests to pass and post a comment on a chosen repository and issue using the configured GITHUB_TOKEN.

Risk Assessment

The vulnerability could allow an attacker to post comments on GitHub repositories, potentially leading to phishing or social engineering.

Recommendation

It is recommended to fix the verification condition in the github-issue-bot code to properly require and verify the HMAC signature.

Related vulnerabilities

Original NVD description (English source)

The github-issue-bot templates in appwrite/templates verify the GitHub webhook signature with an inverted condition. verifyWebhook in node/github-issue-bot/src/github.js and in node-typescript/github-issue-bot/src/github.ts returns "typeof signature !== 'string' || (await verify(...))", so when the X-Hub-Signature-256 header is absent the first operand is true, the logical OR short-circuits, and the function reports success without performing any HMAC verification. main.js rejects a request only when verifyWebhook returns false, so an unauthenticated request carrying no signature passes the check. Processing then continues to postComment, which takes the repository and issue objects directly from the request body, letting the caller direct the deployed function to post a comment on a repository and issue of their choosing using the configured GITHUB_TOKEN, with the issue author login from the body interpolated into the comment text.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS