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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 common Node.js upload middleware, can be forced into resource exhaustion if a client drops a connection during a file upload. For businesses, the main risk is service disruption on applications that accept uploads. The published fix is upgrading Multer to version 2.1.0.

Executive priority

Treat as high priority for any public upload service because the stated business impact is outage risk, not data theft. Patch quickly where Multer handles uploads exposed to untrusted users.

Technical view

CVE-2026-2359 is a network-reachable, unauthenticated denial-of-service issue in expressjs/multer before 2.1.0. The CVE cites CWE-772 and CVSS 4.0 score 8.7, with high availability impact and no stated confidentiality or integrity impact. The source bundle names no workaround.

Likely exposure

Exposure is likely in Node.js or Express applications using Multer before 2.1.0 to process multipart/form-data uploads, especially internet-facing upload endpoints that accept untrusted client connections.

Exploitation context

The source bundle does not show CISA KEV listing or cited active exploitation. It describes a denial-of-service condition triggered by dropped upload connections, but does not provide evidence of exploitation in the wild.

Researcher notes

Evidence is strongest for affected package, impact, CVSS, CWE, and fixed version. The provided affected-version structure is inconsistent with the description, so use the advisory description of versions before 2.1.0 as the actionable basis.

Mitigation direction

  • Upgrade expressjs/multer to version 2.1.0 or later.
  • Prioritize public upload endpoints and unauthenticated file-upload routes.
  • If unable to upgrade immediately, check vendor guidance; no workaround is named in sources.
  • Review downstream vendor advisories if Multer is bundled through a platform package.

Validation and detection

  • Inventory applications and dependencies for expressjs/multer usage.
  • Confirm deployed Multer versions are 2.1.0 or later.
  • Identify routes accepting multipart/form-data uploads from untrusted clients.
  • Verify dependency lockfiles and runtime containers reflect the patched version.
  • Check monitoring for availability degradation around upload endpoints.
Prepared
Confidence
high
Sources
6

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.

Open ATT&CK lookup
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.

Open CWE intelligenceSame-CWE CVEs