Vulnerability-Lookup

FKIE_CVE-2026-77063

Vulnerability from fkie_nvd - Published: 2026-08-28 22:16 - Updated: 2026-09-02 14:46

Severity

3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Summary

multer is a middleware for handling multipart/form-data in Node.js. When an application uses an asynchronous fileFilter together with the fileSize limit, a race condition in multer's file stream handling can allow a file that exceeds the configured size limit to bypass the size-limit rejection. All versions before 2.3.0 are affected. The impact is limited because the underlying multipart parser still truncates the stream at the size limit, so this is a bypass of the limit rejection rather than uncontrolled resource consumption. The issue is fixed in multer 2.3.0. Upgrade to multer 2.3.0 to remediate.

References

	URL	Tags
	ce714d77-add3-4f53-aff5-83d477b104bb	https://cna.openjsf.org/security-advisories.html	Vendor Advisory
	ce714d77-add3-4f53-aff5-83d477b104bb	https://github.com/expressjs/multer/security/advisories/GHSA-qvfw-j98x-7q72	Vendor Advisory, Mitigation

Impacted products

	Vendor	Product	Version
	expressjs	multer	*

JSON

To clipboard

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          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/multer",
          "product": "multer",
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              "version": "0",
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              "version": "2.3.0",
              "versionType": "semver"
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    }
  ],
  "id": "CVE-2026-77063",
  "lastModified": "2026-09-02T14:46:51.367",
  "metrics": {
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          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
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      "type": "Secondary"
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}

CVE-2026-77063 (GCVE-0-2026-77063)

Vulnerability from cvelistv5 – Published: 2026-08-28 19:54 – Updated: 2026-08-31 18:40

Title

multer vulnerable to file size limit bypass via async fileFilter race condition

Summary

Severity

3.7 (Low)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-31 18:40 UTC

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Assigner

openjs CNA under the redhat root

CNA scorecard C 65/100 over 114 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/expressjs/multer/security/advi…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
multer	multer	Affected: 0 , < 2.3.0 (semver) Unaffected: 2.3.0 (semver)

Credits

ThinkerHao bjohansebas UlisesGascon

Show details on NVD website

JSON

To clipboard

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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.
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.

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