CVE-2026-72861 Appwrite Templates github-issue-bot Skips Webhook Signature Verification When the X-Hub-Signature-256 Header Is Absent
Attackers can bypass webhook signature verification to post arbitrary comments on GitHub issues using the bot's credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-72861?
CVE-2026-72861 is a medium-severity vulnerability in appwrite templates, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-347
Which versions are affected by CVE-2026-72861?
How do I fix CVE-2026-72861?
No fix has been published for CVE-2026-72861 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-72861 being exploited?
There is no known exploitation of CVE-2026-72861 in the wild and no public exploit code.
Sources
Also known as GHSA-785c-v4m5-q4wg.