CVE-2026-72861 (GCVE-0-2026-72861)

Vulnerability from cvelistv5 – Published: 2026-08-20 19:48 – Updated: 2026-08-21 21:45
VLAI
Title
Appwrite Templates github-issue-bot Skips Webhook Signature Verification When the X-Hub-Signature-256 Header Is Absent
Summary
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.
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-21 21:33 UTC
CWE
  • CWE-347 - Improper Verification of Cryptographic Signature
Impacted products
Vendor Product Version CPE status
appwrite templates Affected: 0 , ≤ 1.1.2 (semver)
guessed Create a notification for this product.
Date Public
2026-05-26 00:00
Show details on NVD website

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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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