# 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.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Aug 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-785c-v4m5-q4wg

## 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 (Improper Verification of Cryptographic Signature)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72861 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-72861 in the wild and no public exploit code.

Affected product: appwrite templates. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72861/ (Markdown: https://insights.sbomify.com/CVE-2026-72861/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72861
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72861
- OSV: https://osv.dev/vulnerability/CVE-2026-72861

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72861/
Summaries are generated and may contain mistakes; the official description above is the record.