FKIE_CVE-2026-9679
Vulnerability from fkie_nvd - Published: 2026-06-17 18:18 - Updated: 2026-06-17 20:20
Severity
Summary
Impact:
undici's cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 §5.4 does not specify any decoding and browsers do not decode either.
Applications that parse a Set-Cookie header and then forward the parsed value into a response header (proxies, middleware, SSR frameworks) become vulnerable to HTTP response header injection: an attacker-controlled upstream can inject arbitrary Set-Cookie, Location, or Cache-Control headers into the application's downstream response, enabling session fixation, open redirect, or cache poisoning.
Affected applications are those that use undici's cookie parsing (parseSetCookie, parseCookie, getSetCookies) and forward the parsed cookie value into a response header.
This was introduced in undici 7.0.0 via PR #3789.
Patches:
Upgrade to undici v6.26.0, v7.28.0 or v8.5.0.
Workarounds:
If upgrade is not immediately possible, do not forward values returned by parseSetCookie/parseCookie/getSetCookies directly into response headers; sanitize the value first to strip or reject CR, LF, NUL, ;, and = bytes.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:npm/undici",
"product": "undici",
"vendor": "undici",
"versions": [
{
"lessThan": "6.26.0",
"status": "affected",
"version": "0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.26.0",
"versionType": "semver"
},
{
"lessThan": "7.28.0",
"status": "affected",
"version": "7.0.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.28.0",
"versionType": "semver"
},
{
"lessThan": "8.5.0",
"status": "affected",
"version": "8.0.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "8.5.0",
"versionType": "semver"
}
]
}
],
"source": "ce714d77-add3-4f53-aff5-83d477b104bb"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Impact:\nundici\u0027s cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 \u00a75.4 does not specify any decoding and browsers do not decode either.\n\nApplications that parse a Set-Cookie header and then forward the parsed value into a response header (proxies, middleware, SSR frameworks) become vulnerable to HTTP response header injection: an attacker-controlled upstream can inject arbitrary Set-Cookie, Location, or Cache-Control headers into the application\u0027s downstream response, enabling session fixation, open redirect, or cache poisoning.\n\nAffected applications are those that use undici\u0027s cookie parsing (parseSetCookie, parseCookie, getSetCookies) and forward the parsed cookie value into a response header.\n\nThis was introduced in undici 7.0.0 via PR #3789.\n\nPatches:\nUpgrade to undici v6.26.0, v7.28.0 or v8.5.0.\n\nWorkarounds:\nIf upgrade is not immediately possible, do not forward values returned by parseSetCookie/parseCookie/getSetCookies directly into response headers; sanitize the value first to strip or reject CR, LF, NUL, ;, and = bytes."
}
],
"id": "CVE-2026-9679",
"lastModified": "2026-06-17T20:20:10.920",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.9,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.2,
"impactScore": 3.6,
"source": "ce714d77-add3-4f53-aff5-83d477b104bb",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-9679",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-17T18:31:46.100353Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-06-17T18:18:06.307",
"references": [
{
"source": "ce714d77-add3-4f53-aff5-83d477b104bb",
"url": "https://cna.openjsf.org/security-advisories.html"
},
{
"source": "ce714d77-add3-4f53-aff5-83d477b104bb",
"url": "https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv"
}
],
"sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-93"
}
],
"source": "ce714d77-add3-4f53-aff5-83d477b104bb",
"type": "Secondary"
}
]
}
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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
| Author | Source | Type | Date | Other |
|---|
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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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