NVD / CVE Program· CNA openjs

CVE-2026-5079: multer vulnerable to Denial of Service via deeply nested field names

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: multer multer 2.2.0, 3.0.0-alpha.2.

Low priority for now. Upgrade to multer multer 2.2.0, 3.0.0-alpha.2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Impact: multer versions 1.0.0 through 2.1.1 and 3.0.0-alpha.1 are vulnerable to a Denial of Service via deeply nested field names in multipart form data. The append-field dependency parses bracket notation in field names with no limit on nesting depth, allowing an attacker to force allocation of deeply nested object structures that consume CPU and memory. A single HTTP request with a crafted multipart body is sufficient to exploit this. Patches: Users should upgrade to multer 2.2.0 (2.x line) or 3.0.0-alpha.2 (3.x prerelease) and configure the new limits.fieldNestingDepth option to the minimum depth their application requires. Workarounds: Set limits.fields to a reasonable value to reduce the number of fields an attacker can send per request. This does not fully mitigate the issue but limits the impact.

HighCVSS 7.5 · v3.1—No exploit Fix available

GHSA-72gw-mp4g-v24j

Published: Jun 15, 2026
Updated: Jun 17, 2026
EPSS: 0.2% · 20th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · openjs: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
expressjs	multer	cpe:2.3:a:expressjs:multer

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

expressjs multer1.0.0 and later · before 2.2.0
expressjs multer3.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (openjs). Independent of NVD's CPE analysis and usually ahead of it.

multer multer
- 2.2.0, 3.0.0-alpha.2not affected
- 1.0.0 and later · before 2.2.0affected · semver
- 3.0.0-alpha.1 and later · before 3.0.0-alpha.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
npm	multer	from 1.0.0 · before 2.2.0	2.2.0
npm	multer	from 3.0.0-alpha.1 · before 3.0.0-alpha.2	3.0.0-alpha.2

Same product

expressjs: all records

Other highest-scoring records for the same primary product.

CVE-2026-3520Multer vulnerable to Denial of Service via uncontrolled recursion
34Monitor
CVE-2026-3304Multer vulnerable to Denial of Service via incomplete cleanup
34Monitor
CVE-2026-2359Multer vulnerable to Denial of Service via resource exhaustion
34Monitor

Published before and after this one in the same product

← EarlierCVE-2025-48997Jun 3, 2025 · Multer vulnerable to Denial of Service via unhandled exception
34Monitor
← EarlierCVE-2025-7338Jul 17, 2025 · Multer vulnerable to Denial of Service via unhandled exception from malformed request
30Monitor
Later →CVE-2026-5038Jun 15, 2026 · multer vulnerable to Denial of Service via incomplete cleanup of aborted uploads
30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
multer multer	2.2.0	Vendor (CNA)
multer multer	3.0.0-alpha.2	Vendor (CNA)
npm:multer	2.2.0	Package registry (OSV)
npm:multer	3.0.0-alpha.2	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

tndud042713reporter
UlisesGasconremediation developer

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-7703774 days apartmulter vulnerable to Denial of Service via file descriptor leak on aborted uploads
30Monitor
CVE-2026-8233374 days apartmulter vulnerable to Denial of Service via oversized array index in field names
30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

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

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}