Answer in brief
CVE-2026-15157 records a Medium severity security vulnerability in undici vulnerable to CRLF Injection via blob-like body 'type' property. The source record does not mark it as known exploited. 3 affected packages are mapped in the feed.
Answer in brief
CVE-2026-15157 records a Medium severity security vulnerability in undici vulnerable to CRLF Injection via blob-like body 'type' property. The source record does not mark it as known exploited. 3 affected packages are mapped in the feed.
Update undici to 6.28.0; undici to 7.29.0; undici to 8.9.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-15157 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| undicinpm | <6.28.0 | 6.28.0 |
| undicinpm | >=7.0.0,<7.29.0 | 7.29.0 |
| undicinpm | >=8.0.0,<8.9.0 | 8.9.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-15157 records a Medium severity security vulnerability in undici vulnerable to CRLF Injection via blob-like body 'type' property. The source record does not mark it as known exploited. 3 affected packages are mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for undici, undici, undici.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate undici to 6.28.0; undici to 7.29.0; undici to 8.9.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanVulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-15157 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| undicinpm | <6.28.0 | 6.28.0 |
| undicinpm | >=7.0.0,<7.29.0 | 7.29.0 |
| undicinpm | >=8.0.0,<8.9.0 | 8.9.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
CVE-2026-15157 records a Medium severity security vulnerability in undici vulnerable to CRLF Injection via blob-like body 'type' property. The source record does not mark it as known exploited. 3 affected packages are mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for undici, undici, undici.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard### Impact When an application passes a duck-typed blob-like body to undici's HTTP/1.1 dispatcher (via `request()`, `stream()`, `pipeline()`, or `dispatch()`) with a `.type` derived from untrusted input, an attacker can inject CRLF sequences (`\r\n`) to append arbitrary HTTP headers and potentially smuggle a second request past the upstream. The vulnerable branch in `lib/dispatcher/client-h1.js` pushes `body.type` directly into the outgoing headers with no validation, while every other header path in undici goes through `isValidHeaderValue()`: ```javascript } else if (util.isBlobLike(body) && request.contentType == null && body.type) { headers.push('content-type', body.type) // bypasses isValidHeaderValue() } ``` The bug requires a hand-rolled duck-typed blob object or a Blob subclass with a controlled `.type`. Native `Blob` is safe because its constructor strips CRLF from `.type`. `fetch()` is unaffected because it validates via the `Headers` class. Ecosystem consumers that build duck-typed blob shapes from user input include `form-data-encoder`, `formdata-polyfill`, and `formdata-node`. Same defect class as `CVE-2022-35948` (explicit `content-type` sink, fixed in undici 5.8.2) and `CVE-2026-1527` (`upgrade` option sink, fixed in 6.24.0 / 7.24.0), both closed by adding `isValidHeaderValue()` on their respective sinks. This branch was missed. ### Patches Patched in undici v6.28.0, v7.29.0, and v8.9.0. Users should upgrade to one of these versions or later. ### Workarounds - Set an explicit, validated `content-type` header on the request options (skips the vulnerable branch). - Use a native `Blob` (or `fetch-blob`) instead of a hand-rolled duck-typed object. - Reject control characters in the MIME type before assigning it to `.type`. - Use `fetch()` instead of the non-`fetch` APIs.
### Impact When an application passes a duck-typed blob-like body to undici's HTTP/1.1 dispatcher (via `request()`, `stream()`, `pipeline()`, or `dispatch()`) with a `.type` derived from untrusted input, an attacker can inject CRLF sequences (`\r\n`) to append arbitrary HTTP headers and potentially smuggle a second request past the upstream. The vulnerable branch in `lib/dispatcher/client-h1.js` pushes `body.type` directly into the outgoing headers with no validation, while every other header path in undici goes through `isValidHeaderValue()`: ```javascript } else if (util.isBlobLike(body) && request.contentType == null && body.type) { headers.push('content-type', body.type) // bypasses isValidHeaderValue() } ``` The bug requires a hand-rolled duck-typed blob object or a Blob subclass with a controlled `.type`. Native `Blob` is safe because its constructor strips CRLF from `.type`. `fetch()` is unaffected because it validates via the `Headers` class. Ecosystem consumers that build duck-typed blob shapes from user input include `form-data-encoder`, `formdata-polyfill`, and `formdata-node`. Same defect class as `CVE-2022-35948` (explicit `content-type` sink, fixed in undici 5.8.2) and `CVE-2026-1527` (`upgrade` option sink, fixed in 6.24.0 / 7.24.0), both closed by adding `isValidHeaderValue()` on their respective sinks. This branch was missed. ### Patches Patched in undici v6.28.0, v7.29.0, and v8.9.0. Users should upgrade to one of these versions or later. ### Workarounds - Set an explicit, validated `content-type` header on the request options (skips the vulnerable branch). - Use a native `Blob` (or `fetch-blob`) instead of a hand-rolled duck-typed object. - Reject control characters in the MIME type before assigning it to `.type`. - Use `fetch()` instead of the non-`fetch` APIs.