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CVE Record

CVE-2026-2359: Multer vulnerable to Denial of Service via resource exhaustion

Multer is a node.js middleware for handling `multipart/form-data`. A vulnerability in Multer prior to version 2.1.0 allows an attacker to trigger a Denial of Service (DoS) by dropping connection during file upload, potentially causing resource exhaustion. Users should upgrade to version 2.1.0 to receive a patch. No known workarounds are available.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Multer, a Node.js upload middleware, can exhaust server resources when a client drops a file-upload connection. Public sources say versions before 2.1.0 are affected and 2.1.0 contains the fix. This is a service-availability risk, not a data theft issue based on the provided evidence.

Executive priority

Treat this as a high-priority availability issue for public upload services. It can disrupt customer-facing systems without authentication, but the provided sources do not indicate data compromise or active exploitation.

Technical view

CVE-2026-2359 is a CWE-772 resource-release flaw in Multer multipart upload handling. The CVSS 4.0 score is 8.7, with network attack vector, low complexity, no privileges, no user interaction, and high availability impact. The source bundle names no confidentiality or integrity impact.

Likely exposure

Exposure is most likely in Node.js or Express applications using Multer before 2.1.0 on file-upload routes, especially public upload endpoints. Dependency scanners, lockfiles, and SBOMs should confirm whether vulnerable Multer versions are present.

Exploitation context

The bundle does not show CISA KEV listing or confirmed active exploitation. The described attack requires network access to an upload endpoint and abuses connection drops during file upload to cause resource exhaustion.

Researcher notes

Key evidence comes from the GitHub advisory, CVE record, and referenced fix commit. The source bundle states no known workarounds. Affected-version metadata appears sparse, so validate real exposure through dependency artifacts rather than CPE matching alone.

Mitigation direction

  • Upgrade Multer to version 2.1.0 or later.
  • Prioritize internet-facing upload services using Multer.
  • Check Red Hat advisories if consuming Multer through Red Hat-supported products.
  • If immediate upgrade is blocked, monitor vendor guidance; no workaround is named.
  • Review upload service capacity and operational alerting for resource exhaustion.

Validation and detection

  • Inspect package manifests and lockfiles for Multer versions below 2.1.0.
  • Search SBOM and dependency inventory for expressjs/multer usage.
  • Map all application routes that accept multipart file uploads.
  • Confirm deployed artifacts include Multer 2.1.0 or later.
  • Review logs and metrics for abnormal abandoned uploads and resource spikes.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-772: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-2359 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (4.0)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
10Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N——openjs
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-2359Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPmulter: Multer: Denial of Service via dropped file upload connections
other:Red Hat severity ratingcvssV3_1
  • 2026-02-27T16:01:27.340Z: Reported to Red Hat.
  • 2026-02-27T15:42:08.088Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
expressjsmulter0.0.0unaffected
Weakness

CWE details

CWE-772

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-772 · source CWE mapping

Missing Release of Resource after Effective Lifetime

Missing Release of Resource after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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