undici does not validate the type property of a duck-typed blob-like request body before using it as the Content-Type header on the HTTP/1.1 dispatcher. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, an application that passes a hand-rolled blob-like body (via request, stream, pipeline, or dispatch) whose type is derived from untrusted input allows an attacker to inject CRLF sequences and append arbitrary HTTP headers, potentially smuggling a second request past the upstream. Native Blob objects are safe because their constructor strips CRLF from the type, and fetch is unaffected because it validates headers, but ecosystem libraries that build duck-typed blob shapes from user input can reach the vulnerable path. This is the same defect class as CVE-2022-35948 and CVE-2026-1527, on a header sink that the earlier fixes did not cover. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.
Advisories
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Fixes
Solution
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Workaround
No workaround given by the vendor.
References
History
Wed, 29 Jul 2026 22:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Undici
Undici undici |
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| Vendors & Products |
Undici
Undici undici |
Wed, 29 Jul 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | undici does not validate the type property of a duck-typed blob-like request body before using it as the Content-Type header on the HTTP/1.1 dispatcher. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, an application that passes a hand-rolled blob-like body (via request, stream, pipeline, or dispatch) whose type is derived from untrusted input allows an attacker to inject CRLF sequences and append arbitrary HTTP headers, potentially smuggling a second request past the upstream. Native Blob objects are safe because their constructor strips CRLF from the type, and fetch is unaffected because it validates headers, but ecosystem libraries that build duck-typed blob shapes from user input can reach the vulnerable path. This is the same defect class as CVE-2022-35948 and CVE-2026-1527, on a header sink that the earlier fixes did not cover. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0. | |
| Title | undici vulnerable to CRLF Injection via blob-like body 'type' property | |
| Weaknesses | CWE-93 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-07-29T21:17:44.740Z
Reserved: 2026-07-08T20:03:17.332Z
Link: CVE-2026-15157
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OpenCVE Enrichment
Updated: 2026-07-29T22:30:04Z
Weaknesses