Vulnerability-Lookup

CVE-2026-115866 (GCVE-0-2026-115866)

Vulnerability from cvelistv5 – Published: 2026-10-30 12:45 – Updated: 2026-10-30 12:45

Title

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies

Summary

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies. A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads. A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Severity

No CVSS data available.

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

CPANSec CNA under the redhat root

CNA scorecard C 62/100 over 343 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/kazuho/Starlet/commit/229ea56b…	patch
https://metacpan.org/release/KAZUHO/Starlet-0.33/…	release-notes

Impacted products

1 product

Vendor	Product	Version	CPE status
		Affected: 0.20 , < 0.33 (custom)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "modules": [
            "Starlet"
          ],
          "packageName": "Starlet",
          "packageURL": "pkg:cpan/Starlet",
          "programFiles": [
            "lib/Starlet/Server.pm"
          ],
          "programRoutines": [
            {
              "name": "Starlet::Server::handle_connection"
            }
          ],
          "repo": "https://github.com/kazuho/Starlet",
          "versions": [
            {
              "lessThan": "0.33",
              "status": "affected",
              "version": "0.20",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.\n\nA chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.\n\nA remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1333",
              "description": "CWE-1333 Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:45:39.814Z",
        "orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "shortName": "CPANSec"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kazuho/Starlet/commit/229ea56b3b50028e2a644156317e8d0e7cf68a1f.patch"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://metacpan.org/release/KAZUHO/Starlet-0.33/changes"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to Starlet 0.33 or later."
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies",
      "x_generator": {
        "engine": "cpansec-cna-tool 0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
    "assignerShortName": "CPANSec",
    "cveId": "CVE-2026-115866",
    "datePublished": "2026-10-30T12:45:39.814Z",
    "dateReserved": "2026-10-23T17:41:34.521Z",
    "dateUpdated": "2026-10-30T12:45:39.814Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-115866",
      "date": "2026-10-31",
      "epss": "0.00239",
      "percentile": "0.15079"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "collectionURL": "https://cpan.org/modules",
                "defaultStatus": "unaffected",
                "modules": [
                  "Starlet"
                ],
                "packageName": "Starlet",
                "packageURL": "pkg:cpan/Starlet",
                "programFiles": [
                  "lib/Starlet/Server.pm"
                ],
                "programRoutines": [
                  {
                    "name": "Starlet::Server::handle_connection"
                  }
                ],
                "repo": "https://github.com/kazuho/Starlet",
                "versions": [
                  {
                    "lessThan": "0.33",
                    "status": "affected",
                    "version": "0.20",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.\n\nA chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.\n\nA remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called."
          }
        ],
        "id": "CVE-2026-115866",
        "lastModified": "2026-10-30T17:13:54.187",
        "metrics": {},
        "published": "2026-10-30T13:18:31.070",
        "references": [
          {
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
            "url": "https://github.com/kazuho/Starlet/commit/229ea56b3b50028e2a644156317e8d0e7cf68a1f.patch"
          },
          {
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
            "url": "https://metacpan.org/release/KAZUHO/Starlet-0.33/changes"
          }
        ],
        "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-1333"
              }
            ],
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "current_release_date": "2026-10-30T15:04:19+00:00",
      "cve": "CVE-2026-115866",
      "id": "CVE-2026-115866",
      "initial_release_date": "2026-10-30T12:45:39.814000+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "perl-starlet: Starlet: Denial of Service via regular expression backtracking",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-115866.json",
      "version": "3"
    }
  }
}

FKIE_CVE-2026-115866

Vulnerability from fkie_nvd - Published: 2026-10-30 13:18 - Updated: 2026-10-30 17:13

Severity

Summary

References

	URL	Tags
	9b29abf9-4ab0-4765-b253-1875cd9b441e	https://github.com/kazuho/Starlet/commit/229ea56b3b50028e2a644156317e8d0e7cf68a1f.patch
	9b29abf9-4ab0-4765-b253-1875cd9b441e	https://metacpan.org/release/KAZUHO/Starlet-0.33/changes

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "modules": [
            "Starlet"
          ],
          "packageName": "Starlet",
          "packageURL": "pkg:cpan/Starlet",
          "programFiles": [
            "lib/Starlet/Server.pm"
          ],
          "programRoutines": [
            {
              "name": "Starlet::Server::handle_connection"
            }
          ],
          "repo": "https://github.com/kazuho/Starlet",
          "versions": [
            {
              "lessThan": "0.33",
              "status": "affected",
              "version": "0.20",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.\n\nA chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.\n\nA remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called."
    }
  ],
  "id": "CVE-2026-115866",
  "lastModified": "2026-10-30T17:13:54.187",
  "metrics": {},
  "published": "2026-10-30T13:18:31.070",
  "references": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "url": "https://github.com/kazuho/Starlet/commit/229ea56b3b50028e2a644156317e8d0e7cf68a1f.patch"
    },
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "url": "https://metacpan.org/release/KAZUHO/Starlet-0.33/changes"
    }
  ],
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ],
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary"
    }
  ]
}

GHSA-8JC4-2M4J-6VF8

Vulnerability from github – Published: 2026-10-30 15:34 – Updated: 2026-10-30 15:34

Details

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-115866"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-30T13:18:31Z",
    "severity": null
  },
  "details": "Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.\n\nA chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.\n\nA remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.",
  "id": "GHSA-8jc4-2m4j-6vf8",
  "modified": "2026-10-30T15:34:30Z",
  "published": "2026-10-30T15:34:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115866"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kazuho/Starlet/commit/229ea56b3b50028e2a644156317e8d0e7cf68a1f.patch"
    },
    {
      "type": "WEB",
      "url": "https://metacpan.org/release/KAZUHO/Starlet-0.33/changes"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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

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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.
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CVE-2026-115866 (GCVE-0-2026-115866)

FKIE_CVE-2026-115866

GHSA-8JC4-2M4J-6VF8

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