Vulnerability-Lookup

GHSA-M8RV-5G2X-5CG5

Vulnerability from github – Published: 2026-08-03 19:33 – Updated: 2026-08-03 19:33

Summary

undici vulnerable to CRLF Injection via blob-like body 'type' property

Details

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():

} 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.

Severity

4.2 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.28.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.29.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-15157"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-93"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-03T19:33:53Z",
    "nvd_published_at": "2026-07-29T22:16:52Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nWhen an application passes a duck-typed blob-like body to undici\u0027s 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.\n\nThe 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()`:\n\n```javascript\n} else if (util.isBlobLike(body) \u0026\u0026 request.contentType == null \u0026\u0026 body.type) {\n  headers.push(\u0027content-type\u0027, body.type)  // bypasses isValidHeaderValue()\n}\n```\n\nThe 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`.\n\nSame 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.\n\n### Patches\n\nPatched in undici v6.28.0, v7.29.0, and v8.9.0. Users should upgrade to one of these versions or later.\n\n### Workarounds\n\n- Set an explicit, validated `content-type` header on the request options (skips the vulnerable branch).\n- Use a native `Blob` (or `fetch-blob`) instead of a hand-rolled duck-typed object.\n- Reject control characters in the MIME type before assigning it to `.type`.\n- Use `fetch()` instead of the non-`fetch` APIs.",
  "id": "GHSA-m8rv-5g2x-5cg5",
  "modified": "2026-08-03T19:33:53Z",
  "published": "2026-08-03T19:33:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/security/advisories/GHSA-m8rv-5g2x-5cg5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15157"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/33928bc24f742ea8422ed90d17f2e0cc83e4d09d"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/740a0b7c173cb4a83a5b693e96e8f3a116cfc400"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/7d3cf924c262c486bc77f951348f4e5c847b7b42"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nodejs/undici"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v6.28.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v7.29.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v8.9.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "undici vulnerable to CRLF Injection via blob-like body \u0027type\u0027 property"
}

CVE-2026-15157 (GCVE-0-2026-15157)

Vulnerability from cvelistv5 – Published: 2026-07-29 21:17 – Updated: 2026-07-30 15:18

Title

undici vulnerable to CRLF Injection via blob-like body 'type' property

Summary

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.

Severity

4.2 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-30 14:20 UTC

CWE

CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

Assigner

openjs CNA under the redhat root

CNA scorecard C 66/100 over 142 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/nodejs/undici/security/advisor…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
undici	undici	Affected: 0 , < 6.28.0 (semver) Unaffected: 6.28.0 (semver) Affected: 7.0.0 , < 7.29.0 (semver) Unaffected: 7.29.0 (semver) Affected: 8.0.0 , < 8.9.0 (semver) Unaffected: 8.9.0 (semver)

Credits

mcollina UlisesGascon

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-15157",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-30T14:20:35.188091Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-30T15:18:02.970Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/undici",
          "product": "undici",
          "vendor": "undici",
          "versions": [
            {
              "lessThan": "6.28.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.28.0",
              "versionType": "semver"
            },
            {
              "lessThan": "7.29.0",
              "status": "affected",
              "version": "7.0.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.29.0",
              "versionType": "semver"
            },
            {
              "lessThan": "8.9.0",
              "status": "affected",
              "version": "8.0.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "8.9.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "mcollina"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "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."
            }
          ],
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 4.2,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-93",
              "description": "CWE-93: Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-29T21:17:44.740Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/nodejs/undici/security/advisories/GHSA-m8rv-5g2x-5cg5"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "undici vulnerable to CRLF Injection via blob-like body \u0027type\u0027 property",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-15157",
    "datePublished": "2026-07-29T21:17:44.740Z",
    "dateReserved": "2026-07-08T20:03:17.332Z",
    "dateUpdated": "2026-07-30T15:18:02.970Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

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 model, served locally by ML-Gateway. 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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

Action not permitted