CVE-2026-72861 (GCVE-0-2026-72861)
Vulnerability from cvelistv5
Published
2026-08-20 19:48
Modified
2026-08-21 21:45
Severity ?
5.8 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
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
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
VLAI Severity ?
EPSS score ?
CWE
- CWE-347 - Improper Verification of Cryptographic Signature
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.
References
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-72861",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-21T21:33:32.540767Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
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"providerMetadata": {
"dateUpdated": "2026-08-21T21:45:50.993Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "templates",
"programFiles": [
"node/github-issue-bot/src/github.js",
"node-typescript/github-issue-bot/src/github.ts"
],
"repo": "https://github.com/appwrite/templates",
"vendor": "appwrite",
"versions": [
{
"lessThanOrEqual": "1.1.2",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
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],
"credits": [
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"lang": "en",
"type": "reporter",
"value": "potdf-bl4ck-570rm"
}
],
"datePublic": "2026-05-26T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"value": "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 !== \u0027string\u0027 || (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."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
"version": "3.1"
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{
"cvssV4_0": {
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"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
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"description": "Improper Verification of Cryptographic Signature",
"lang": "en",
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"providerMetadata": {
"dateUpdated": "2026-08-20T19:48:51.102Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
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"references": [
{
"name": "GitHub Issue #350",
"tags": [
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],
"url": "https://github.com/appwrite/templates/issues/350"
},
{
"name": "verifyWebhook in the node template at 1.1.2",
"tags": [
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"url": "https://github.com/appwrite/templates/blob/1.1.2/node/github-issue-bot/src/github.js"
},
{
"name": "verifyWebhook in the node-typescript template at 1.1.2",
"tags": [
"technical-description"
],
"url": "https://github.com/appwrite/templates/blob/1.1.2/node-typescript/github-issue-bot/src/github.ts"
},
{
"name": "main.js gating on verifyWebhook and calling postComment",
"tags": [
"technical-description"
],
"url": "https://github.com/appwrite/templates/blob/1.1.2/node/github-issue-bot/src/main.js"
},
{
"tags": [
"product"
],
"url": "https://github.com/appwrite/templates"
},
{
"name": "VulnCheck Advisory: Appwrite Templates github-issue-bot Skips Webhook Signature Verification When the X-Hub-Signature-256 Header Is Absent",
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/appwrite-templates-github-issue-bot-skips-webhook-signature-verification-when-the-x-hub-signature-256-header-is-absent"
}
],
"title": "Appwrite Templates github-issue-bot Skips Webhook Signature Verification When the X-Hub-Signature-256 Header Is Absent",
"x_generator": {
"engine": "vulncheck-endgame"
}
}
},
"cveMetadata": {
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"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-72861",
"datePublished": "2026-08-20T19:48:51.102Z",
"dateReserved": "2026-08-10T15:16:31.372Z",
"dateUpdated": "2026-08-21T21:45:50.993Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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