BREW-NVCHECKER-CVE-2026-49853 (GHSA-3X9G-8VMP-WQVF)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:19 – Updated: 2026-09-17 18:30 – Source website
VLAI
Summary
Tornado: Authorization header forwarded across cross-origin redirects in SimpleAsyncHTTPClient
Details
Summary
When SimpleAsyncHTTPClient follows a 3xx redirect, it shallow-copies the original HTTPRequest, rewrites the URL, decrements max_redirects, and removes only the Host header. It does not clear Authorization, auth_username, auth_password, or auth_mode when the redirect target changes origin.
As a result, credentials intended for one origin can be forwarded to a different origin when follow_redirects=True, which is the default.
Beginning in Tornado 6.5.6, SimpleAsyncHTTPClient matches the default behavior of libcurl (and therefore CurlAsyncHTTPClient): When a redirect changes the scheme, host, or port of the url, the Authorization and Cookie headers will be removed when following the redirect.
Severity
7.7 (High)
References
| URL | Type | |
|---|---|---|
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.6"
},
"package": {
"ecosystem": "Homebrew",
"name": "nvchecker",
"purl": "pkg:brew/nvchecker"
},
"ranges": [
{
"events": [
{
"introduced": "2.7"
},
{
"fixed": "2.20_2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"details": "## Summary\n\nWhen SimpleAsyncHTTPClient follows a 3xx redirect, it shallow-copies the original HTTPRequest, rewrites the URL, decrements max_redirects, and removes only the Host header. It does not clear Authorization, auth_username, auth_password, or auth_mode when the redirect target changes origin.\n\nAs a result, credentials intended for one origin can be forwarded to a different origin when follow_redirects=True, which is the default.\n\nBeginning in Tornado 6.5.6, `SimpleAsyncHTTPClient` matches the default behavior of `libcurl` (and therefore `CurlAsyncHTTPClient`): When a redirect changes the scheme, host, or port of the url, the `Authorization` and `Cookie` headers will be removed when following the redirect.",
"id": "BREW-nvchecker-CVE-2026-49853",
"modified": "2026-09-17T18:30:47Z",
"published": "2026-08-13T17:19:21Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-3x9g-8vmp-wqvf"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Authorization header forwarded across cross-origin redirects in SimpleAsyncHTTPClient",
"upstream": [
"GHSA-3x9g-8vmp-wqvf",
"CVE-2026-49853",
"PYSEC-2026-3387"
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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