Vulnerability-Lookup

CVE-2026-42545 (GCVE-0-2026-42545)

Vulnerability from cvelistv5 – Published: 2026-05-12 21:51 – Updated: 2026-05-14 12:35

Title

Granian: DoS via WSGI response header panic

Summary

Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.

Severity

5.9 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-248 - Uncaught Exception
CWE-755 - Improper Handling of Exceptional Conditions

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/emmett-framework/granian/secur…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
emmett-framework	granian	Affected: >= 0.2.0, < 2.7.4

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42545",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-14T12:35:15.328399Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-14T12:35:27.130Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "granian",
          "vendor": "emmett-framework",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.2.0, \u003c 2.7.4"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-248",
              "description": "CWE-248: Uncaught Exception",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-755",
              "description": "CWE-755: Improper Handling of Exceptional Conditions",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-12T21:51:47.473Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj"
        }
      ],
      "source": {
        "advisory": "GHSA-f5p7-9fr5-8jmj",
        "discovery": "UNKNOWN"
      },
      "title": "Granian: DoS via WSGI response header panic"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-42545",
    "datePublished": "2026-05-12T21:51:47.473Z",
    "dateReserved": "2026-04-28T16:56:50.191Z",
    "dateUpdated": "2026-05-14T12:35:27.130Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-42545",
      "date": "2026-06-07",
      "epss": "0.00052",
      "percentile": "0.16765"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-42545\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-05-12T22:16:34.600\",\"lastModified\":\"2026-05-14T13:16:18.370\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.2,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-248\"},{\"lang\":\"en\",\"value\":\"CWE-755\"}]}],\"references\":[{\"url\":\"https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-42545\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-14T12:35:15.328399Z\"}}}], \"references\": [{\"url\": \"https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-14T12:35:09.326Z\"}}], \"cna\": {\"title\": \"Granian: DoS via WSGI response header panic\", \"source\": {\"advisory\": \"GHSA-f5p7-9fr5-8jmj\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.9, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"emmett-framework\", \"product\": \"granian\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 0.2.0, \u003c 2.7.4\"}]}], \"references\": [{\"url\": \"https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj\", \"name\": \"https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj\", \"tags\": [\"x_refsource_CONFIRM\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-248\", \"description\": \"CWE-248: Uncaught Exception\"}]}, {\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-755\", \"description\": \"CWE-755: Improper Handling of Exceptional Conditions\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-05-12T21:51:47.473Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-42545\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-14T12:35:27.130Z\", \"dateReserved\": \"2026-04-28T16:56:50.191Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-05-12T21:51:47.473Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-42545

Vulnerability from fkie_nvd - Published: 2026-05-12 22:16 - Updated: 2026-05-14 13:16

Severity

5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4."
    }
  ],
  "id": "CVE-2026-42545",
  "lastModified": "2026-05-14T13:16:18.370",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-12T22:16:34.600",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-248"
        },
        {
          "lang": "en",
          "value": "CWE-755"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-F5P7-9FR5-8JMJ

Vulnerability from github – Published: 2026-05-06 21:24 – Updated: 2026-05-13 16:41

Summary

Granian vulnerable to DoS via WSGI response header panic

Details

Summary

Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error.

This issue requires a buggy or attacker-influenced WSGI application to emit invalid headers. It is not a parser bug in Granian's request path. The security impact is that application mistakes which should result in a 500 instead kill the worker process.

Details

https://github.com/emmett-framework/granian/blob/bdd5b0fbbb2aca6f2f4c0d2700c244d190958035/src/wsgi/io.rs#L39-L42

If either conversion fails, .unwrap() panics. In release builds Granian uses panic = "abort", so the panic terminates the worker.

Preconditions

The attacker must be able to influence a header name or value produced by the WSGI application, or the application must otherwise generate invalid headers.

Examples include:

a header name containing a space
a header value containing \r\n
a header value containing a null byte

These are realistic failure modes for applications that reflect user-controlled data into headers such as Location, Content Disposition, or custom response headers.

PoC

Step 1

start Granian with the PoC WSGI app

# app.py
def app(environ, start_response):
    path = environ.get("PATH_INFO", "/")
    if path == "/crash-name":
        headers = [("X Bad Name", "value")]
    elif path == "/crash-value":
        headers = [("Content-Type", "text/html\r\nX-Injected: evil")]
    elif path == "/crash-null":
        headers = [("X-Custom", "value\x00end")]
    else:
        start_response("200 OK", [("Content-Type", "text/plain")])
        return [b"OK - server alive\n"]

    start_response("200 OK", headers)
    return [b"This response kills the worker\n"]

granian --interface wsgi app:app --host 127.0.0.1 --port 8000

Step 2

trigger the crash (any one of these is sufficient)

curl http://127.0.0.1:8000/crash-name
curl http://127.0.0.1:8000/crash-value
curl http://127.0.0.1:8000/crash-null

Expected result:

the worker aborts after any of the crash paths
subsequent requests fail until the worker is restarted

Impact

Worker process denial of service
A single bad response kills one worker
Application bugs become process crashes instead of request-scoped failures

Severity

5.9 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "granian"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.2.0"
            },
            {
              "fixed": "2.7.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42545"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248",
      "CWE-755"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-06T21:24:56Z",
    "nvd_published_at": "2026-05-12T22:16:34Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nGranian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses `.unwrap()` on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error.\n\nThis issue requires a buggy or attacker-influenced WSGI application to emit invalid headers. It is not a parser bug in Granian\u0027s request path. The security impact is that application mistakes which should result in a `500` instead kill the worker process.\n\n### Details\n\nhttps://github.com/emmett-framework/granian/blob/bdd5b0fbbb2aca6f2f4c0d2700c244d190958035/src/wsgi/io.rs#L39-L42\n\nIf either conversion fails, `.unwrap()` panics. In release builds Granian uses `panic = \"abort\"`, so the panic terminates the worker.\n\n\n#### Preconditions\n\nThe attacker must be able to influence a header name or value produced by the WSGI application, or the application must otherwise generate invalid headers.\n\nExamples include:\n\n- a header name containing a space\n- a header value containing `\\r\\n`\n- a header value containing a null byte\n\nThese are realistic failure modes for applications that reflect user-controlled data into headers such as `Location`, `Content Disposition`, or custom response headers.\n\n### PoC\n\n#### Step 1\n\nstart Granian with the PoC WSGI app\n\n```python\n# app.py\ndef app(environ, start_response):\n    path = environ.get(\"PATH_INFO\", \"/\")\n    if path == \"/crash-name\":\n        headers = [(\"X Bad Name\", \"value\")]\n    elif path == \"/crash-value\":\n        headers = [(\"Content-Type\", \"text/html\\r\\nX-Injected: evil\")]\n    elif path == \"/crash-null\":\n        headers = [(\"X-Custom\", \"value\\x00end\")]\n    else:\n        start_response(\"200 OK\", [(\"Content-Type\", \"text/plain\")])\n        return [b\"OK - server alive\\n\"]\n\n    start_response(\"200 OK\", headers)\n    return [b\"This response kills the worker\\n\"]\n\n```\n\n```bash\ngranian --interface wsgi app:app --host 127.0.0.1 --port 8000\n```\n\n#### Step 2\n\ntrigger the crash (any one of these is sufficient)\n\n```bash\ncurl http://127.0.0.1:8000/crash-name\ncurl http://127.0.0.1:8000/crash-value\ncurl http://127.0.0.1:8000/crash-null\n```\n\n\nExpected result:\n\n- the worker aborts after any of the crash paths\n- subsequent requests fail until the worker is restarted\n\n\n### Impact\n\n- Worker process denial of service\n- A single bad response kills one worker\n- Application bugs become process crashes instead of request-scoped failures",
  "id": "GHSA-f5p7-9fr5-8jmj",
  "modified": "2026-05-13T16:41:31Z",
  "published": "2026-05-06T21:24:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42545"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/emmett-framework/granian"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Granian vulnerable to DoS via WSGI response header panic"
}

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.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-42545 (GCVE-0-2026-42545)

FKIE_CVE-2026-42545

GHSA-F5P7-9FR5-8JMJ

Summary

Details

Preconditions

PoC

Step 1

Step 2

Impact

Tags

Sightings

Nomenclature