Vulnerability-Lookup

CVE-2026-27601 (GCVE-0-2026-27601)

Vulnerability from cvelistv5 – Published: 2026-03-03 22:38 – Updated: 2026-03-03 22:38

Title

Underscore.js has unlimited recursion in _.flatten and _.isEqual, potential for DoS attack

Summary

Underscore.js is a utility-belt library for JavaScript. Prior to 1.13.8, the _.flatten and _.isEqual functions use recursion without a depth limit. Under very specific conditions, detailed below, an attacker could exploit this in a Denial of Service (DoS) attack by triggering a stack overflow. Untrusted input must be used to create a recursive datastructure, for example using JSON.parse, with no enforced depth limit. The datastructure thus created must be passed to _.flatten or _.isEqual. In the case of _.flatten, the vulnerability can only be exploited if it is possible for a remote client to prepare a datastructure that consists of arrays at all levels AND if no finite depth limit is passed as the second argument to _.flatten. In the case of _.isEqual, the vulnerability can only be exploited if there exists a code path in which two distinct datastructures that were submitted by the same remote client are compared using _.isEqual. For example, if a client submits data that are stored in a database, and the same client can later submit another datastructure that is then compared to the data that were saved in the database previously, OR if a client submits a single request, but its data are parsed twice, creating two non-identical but equivalent datastructures that are then compared. Exceptions originating from the call to _.flatten or _.isEqual, as a result of a stack overflow, are not being caught. This vulnerability is fixed in 1.13.8.

Severity ?

8.2 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

GitHub_M

References

URL

Tags

	https://github.com/jashkenas/underscore/security/…	x_refsource_CONFIRM
	https://github.com/jashkenas/underscore/commit/41…	x_refsource_MISC
	https://github.com/jashkenas/underscore/commit/a6…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	jashkenas	underscore	Affected: < 1.13.8

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "underscore",
          "vendor": "jashkenas",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.13.8"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Underscore.js is a utility-belt library for JavaScript. Prior to 1.13.8, the _.flatten and _.isEqual functions use recursion without a depth limit. Under very specific conditions, detailed below, an attacker could exploit this in a Denial of Service (DoS) attack by triggering a stack overflow. Untrusted input must be used to create a recursive datastructure, for example using JSON.parse, with no enforced depth limit. The datastructure thus created must be passed to _.flatten or _.isEqual. In the case of _.flatten, the vulnerability can only be exploited if it is possible for a remote client to prepare a datastructure that consists of arrays at all levels AND if no finite depth limit is passed as the second argument to _.flatten. In the case of _.isEqual, the vulnerability can only be exploited if there exists a code path in which two distinct datastructures that were submitted by the same remote client are compared using _.isEqual. For example, if a client submits data that are stored in a database, and the same client can later submit another datastructure that is then compared to the data that were saved in the database previously, OR if a client submits a single request, but its data are parsed twice, creating two non-identical but equivalent datastructures that are then compared. Exceptions originating from the call to _.flatten or _.isEqual, as a result of a stack overflow, are not being caught. This vulnerability is fixed in 1.13.8."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-03T22:38:38.955Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/jashkenas/underscore/security/advisories/GHSA-qpx9-hpmf-5gmw",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jashkenas/underscore/security/advisories/GHSA-qpx9-hpmf-5gmw"
        },
        {
          "name": "https://github.com/jashkenas/underscore/commit/411e222eb0ca5d570cc4f6315c02c05b830ed2b4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jashkenas/underscore/commit/411e222eb0ca5d570cc4f6315c02c05b830ed2b4"
        },
        {
          "name": "https://github.com/jashkenas/underscore/commit/a6e23ae9647461ec33ad9f92a2ecfc220eea0a84",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jashkenas/underscore/commit/a6e23ae9647461ec33ad9f92a2ecfc220eea0a84"
        }
      ],
      "source": {
        "advisory": "GHSA-qpx9-hpmf-5gmw",
        "discovery": "UNKNOWN"
      },
      "title": "Underscore.js has unlimited recursion in _.flatten and _.isEqual, potential for DoS attack"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27601",
    "datePublished": "2026-03-03T22:38:38.955Z",
    "dateReserved": "2026-02-20T19:43:14.602Z",
    "dateUpdated": "2026-03-03T22:38:38.955Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-27601\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-03-03T23:15:55.560\",\"lastModified\":\"2026-03-03T23:15:55.560\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Underscore.js is a utility-belt library for JavaScript. Prior to 1.13.8, the _.flatten and _.isEqual functions use recursion without a depth limit. Under very specific conditions, detailed below, an attacker could exploit this in a Denial of Service (DoS) attack by triggering a stack overflow. Untrusted input must be used to create a recursive datastructure, for example using JSON.parse, with no enforced depth limit. The datastructure thus created must be passed to _.flatten or _.isEqual. In the case of _.flatten, the vulnerability can only be exploited if it is possible for a remote client to prepare a datastructure that consists of arrays at all levels AND if no finite depth limit is passed as the second argument to _.flatten. In the case of _.isEqual, the vulnerability can only be exploited if there exists a code path in which two distinct datastructures that were submitted by the same remote client are compared using _.isEqual. For example, if a client submits data that are stored in a database, and the same client can later submit another datastructure that is then compared to the data that were saved in the database previously, OR if a client submits a single request, but its data are parsed twice, creating two non-identical but equivalent datastructures that are then compared. Exceptions originating from the call to _.flatten or _.isEqual, as a result of a stack overflow, are not being caught. This vulnerability is fixed in 1.13.8.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.2,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"references\":[{\"url\":\"https://github.com/jashkenas/underscore/commit/411e222eb0ca5d570cc4f6315c02c05b830ed2b4\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/jashkenas/underscore/commit/a6e23ae9647461ec33ad9f92a2ecfc220eea0a84\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/jashkenas/underscore/security/advisories/GHSA-qpx9-hpmf-5gmw\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}

Sightings

Author	Source	Type	Date

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.

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CVE-2026-27601 (GCVE-0-2026-27601)

Tags

Sightings

Nomenclature