Vulnerability-Lookup

CVE-2026-40345 (GCVE-0-2026-40345)

Vulnerability from cvelistv5 – Published: 2026-08-20 16:33 – Updated: 2026-08-21 16:28

Title

deepmerge-ts: Stack exhaustion when merging recursive object graphs

Summary

deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects. Prior to 8.0.0, the deepmerge, deepmergeCustom, deepmergeInto, and deepmergeIntoCustom APIs do not track visited objects or object pairs when recursively merging records. When two input values contain self-references at the same property path, the merge logic repeatedly revisits the same pair until Node.js raises RangeError: Maximum call stack size exceeded. Applications that merge attacker-controlled recursive object graphs can synchronously crash the affected process or cause repeated worker restarts. Plain JSON input alone cannot create the recursive graph required to trigger the issue. This issue is fixed in version 8.0.0.

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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 16:27 UTC

CWE

CWE-674 - Uncontrolled Recursion

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7760 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/RebeccaStevens/deepmerge-ts/se…	x_refsource_CONFIRM
https://github.com/RebeccaStevens/deepmerge-ts/pull/707	x_refsource_MISC
https://github.com/RebeccaStevens/deepmerge-ts/co…	x_refsource_MISC
https://github.com/RebeccaStevens/deepmerge-ts/re…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
RebeccaStevens	deepmerge-ts	Affected: < 8.0.0	guessed

Show details on NVD website

JSON

To clipboard

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CLEANSTART-2026-ML15245 (CVE-2026-40345)

Vulnerability from cleanstart – Published: 2026-10-08 00:43 – Updated: 2026-10-09 03:49 – Source website

Summary

deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects

Details

Security vulnerability affects the langfuse-worker package. deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects.

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/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

References

URL

Type

	https://github.com/cleanstart-dev/cleanstart-secu…	ADVISORY
	https://osv.dev/vulnerability/CVE-2026-40345	WEB
	https://nvd.nist.gov/vuln/detail/CVE-2026-40345	WEB

JSON

To clipboard

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  "affected": [
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "langfuse-worker",
        "purl": "pkg:apk/cleanstart/langfuse-worker"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.225.9-r3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "credits": [],
  "database_specific": {},
  "details": "Security vulnerability affects the langfuse-worker package. deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects.",
  "id": "CLEANSTART-2026-ML15245",
  "modified": "2026-10-09T03:49:57Z",
  "published": "2026-10-08T00:43:41.973381Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/cleanstart-dev/cleanstart-security-advisories/tree/main/advisories/2026/CLEANSTART-2026-ML15245.json"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/CVE-2026-40345"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40345"
    }
  ],
  "related": [],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects",
  "upstream": [
    "CVE-2026-40345"
  ]
}

FKIE_CVE-2026-40345

Vulnerability from fkie_nvd - Published: 2026-08-20 17:17 - Updated: 2026-09-18 20:09

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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/RebeccaStevens/deepmerge-ts/commit/398492757b3f22a0d7d89b09ce1ae9cd32806c9a
	security-advisories@github.com	https://github.com/RebeccaStevens/deepmerge-ts/pull/707
	security-advisories@github.com	https://github.com/RebeccaStevens/deepmerge-ts/releases/tag/v8.0.0
	security-advisories@github.com	https://github.com/RebeccaStevens/deepmerge-ts/security/advisories/GHSA-ggr8-5vv4-36mx
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/RebeccaStevens/deepmerge-ts/security/advisories/GHSA-ggr8-5vv4-36mx

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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    {
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        {
          "product": "deepmerge-ts",
          "vendor": "RebeccaStevens",
          "versions": [
            {
              "status": "affected",
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    }
  ],
  "id": "CVE-2026-40345",
  "lastModified": "2026-09-18T20:09:01.757",
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          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-40345",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-21T16:27:55.525819Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-20T17:17:29.783",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/commit/398492757b3f22a0d7d89b09ce1ae9cd32806c9a"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/pull/707"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/releases/tag/v8.0.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/security/advisories/GHSA-ggr8-5vv4-36mx"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/security/advisories/GHSA-ggr8-5vv4-36mx"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-674"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-GGR8-5VV4-36MX

Vulnerability from github – Published: 2026-08-17 13:32 – Updated: 2026-08-17 13:32

Summary

DeepmergeTS has stack exhaustion when merging recursive object graphs

Details

Summary

deepmerge() and deepmergeInto() can be crashed with a crafted recursive object graph. When both merged values contain self-references at the same property path, the library recurses until Node throws RangeError: Maximum call stack size exceeded.

Details

Record merging is implemented recursively. For each enumerable key, the library collects the values from every input object and immediately calls the same merge routine on that property.

There is no visited-object tracking, pair tracking, or cycle detection in that recursion. As a result, if two merged records both point back to themselves through the same key path, the merge logic keeps revisiting the same object pair forever.

This is reachable through the real public API:

deepmerge(...)
deepmergeCustom(...)(...)
deepmergeInto(target, ...)
deepmergeIntoCustom(...)(target, ...)

The issue only occurs when recursive object graphs are supplied. Plain JSON alone does not create this condition.

PoC

import { deepmerge, deepmergeInto } from "deepmerge-ts";

const left = {};
left.self = left;

const right = {};
right.self = right;

try {
  deepmerge(left, right);
} catch (error) {
  console.log(error.name, error.message);
  // Expected: the merge should reject or safely handle recursive input without exhausting the stack.
  // Vulnerable behavior: RangeError Maximum call stack size exceeded
}

const target = {};
target.self = target;

const source = {};
source.self = source;

try {
  deepmergeInto(target, source);
} catch (error) {
  console.log(error.name, error.message);
  // Expected: the merge should reject or safely handle recursive input without exhausting the stack.
  // Vulnerable behavior: RangeError Maximum call stack size exceeded
}

Impact

Applications that pass attacker-controlled recursive object graphs into these APIs can be forced into a synchronous crash path. In Node.js services, that can terminate request handling for the affected process or trigger repeated worker restarts until the malicious input is blocked.

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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "deepmerge-ts"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40345"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-17T13:32:13Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`deepmerge()` and `deepmergeInto()` can be crashed with a crafted recursive object graph. When both merged values contain self-references at the same property path, the library recurses until Node throws `RangeError: Maximum call stack size exceeded`.\n\n### Details\n\nRecord merging is implemented recursively. For each enumerable key, the library collects the values from every input object and immediately calls the same merge routine on that property.\n\nThere is no visited-object tracking, pair tracking, or cycle detection in that recursion. As a result, if two merged records both point back to themselves through the same key path, the merge logic keeps revisiting the same object pair forever.\n\nThis is reachable through the real public API:\n\n* `deepmerge(...)`\n* `deepmergeCustom(...)(...)`\n* `deepmergeInto(target, ...)`\n* `deepmergeIntoCustom(...)(target, ...)`\n\nThe issue only occurs when recursive object graphs are supplied. Plain JSON alone does not create this condition.\n\n### PoC\n\n```js\nimport { deepmerge, deepmergeInto } from \"deepmerge-ts\";\n\nconst left = {};\nleft.self = left;\n\nconst right = {};\nright.self = right;\n\ntry {\n  deepmerge(left, right);\n} catch (error) {\n  console.log(error.name, error.message);\n  // Expected: the merge should reject or safely handle recursive input without exhausting the stack.\n  // Vulnerable behavior: RangeError Maximum call stack size exceeded\n}\n\nconst target = {};\ntarget.self = target;\n\nconst source = {};\nsource.self = source;\n\ntry {\n  deepmergeInto(target, source);\n} catch (error) {\n  console.log(error.name, error.message);\n  // Expected: the merge should reject or safely handle recursive input without exhausting the stack.\n  // Vulnerable behavior: RangeError Maximum call stack size exceeded\n}\n```\n\n### Impact\n\nApplications that pass attacker-controlled recursive object graphs into these APIs can be forced into a synchronous crash path. In Node.js services, that can terminate request handling for the affected process or trigger repeated worker restarts until the malicious input is blocked.",
  "id": "GHSA-ggr8-5vv4-36mx",
  "modified": "2026-08-17T13:32:13Z",
  "published": "2026-08-17T13:32:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/security/advisories/GHSA-ggr8-5vv4-36mx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts"
    },
    {
      "type": "WEB",
      "url": "https://github.com/RebeccaStevens/deepmerge-ts/releases/tag/v8.0.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "DeepmergeTS has stack exhaustion when merging recursive object graphs"
}

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.

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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-2026-40345 (GCVE-0-2026-40345)

CLEANSTART-2026-ML15245 (CVE-2026-40345)

FKIE_CVE-2026-40345

GHSA-GGR8-5VV4-36MX

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