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.
This page covers CVE-2026-15157 as tracked by Ubuntu, for the package node-undici. No fixed version has been recorded for this distribution yet.
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
UBUNTU-CVE-2026-15157 is classified as CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection'). The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
UBUNTU-CVE-2026-15157 is recorded against 1 package.
Published on 29 July 2026 and last revised on 6 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
ubuntu.com (Report)
www.cve.org (Report)
github.com (Report)
cna.openjsf.org (Report)
node-undici has other advisories on record. If you are patching this one, these are worth checking on the same host:
These advisories are the same class of weakness (CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')) in other software:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| node-undici | — | — |
References
Similar Threats
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