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Appwrite Templates EUVDEUVD-2026-63579

| CVE-2026-72861 MEDIUM
Improper Verification of Cryptographic Signature (CWE-347)
2026-08-20 VulnCheck GHSA-785c-v4m5-q4wg
Information Disclosure Jwt Attack Templates
6.9
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
6.9 MEDIUM
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
5.8 MEDIUM

Network-reachable with no prerequisites; scope change because GITHUB_TOKEN affects external repositories; integrity limited to comment posting only.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

2
CVSS changed
Aug 20, 2026 - 20:22 NVD
5.8 (MEDIUM) 6.9 (MEDIUM)
Analysis Generated
Aug 20, 2026 - 20:21 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Webhook signature bypass in the appwrite/templates github-issue-bot (≤ 1.1.2) allows any unauthenticated network caller to invoke the bot's comment-posting functionality without a valid GitHub HMAC signature. An inverted boolean condition in verifyWebhook causes requests lacking the X-Hub-Signature-256 header to short-circuit to success, so the body is processed as if it were a legitimate GitHub event. …

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Attack ChainAIDerived

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Vulnerability AssessmentAI

Exploitation The github-issue-bot template must be deployed as a publicly accessible function endpoint with a GITHUB_TOKEN configured with write access to at least one GitHub repository. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 5.8 with vector AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N is appropriate: the attack is trivially executable over the network without credentials or complexity, and the Scope:Changed metric reflects that the configured GITHUB_TOKEN is leveraged to affect GitHub repositories outside the vulnerable application boundary. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation No vendor-released patched version is independently confirmed in the available data - the fix version must be verified by monitoring the upstream repository at https://github.com/appwrite/templates and the tracking issue at https://github.com/appwrite/templates/issues/350. … Detailed patch versions, workarounds, and compensating controls in full report.
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EUVD-2026-63579 vulnerability details – vuln.today
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