Multer vulnerable to Denial of Service via unhandled exception from malformed request
Multer is a node.js middleware for handling `multipart/form-data`. A vulnerability that is present starting in version 1.4.4-lts.1 and prior to version 2.0.2 allows an attacker to trigger a Denial of Service (DoS) by sending a malformed multi-part upload request. This request causes an unhandled exception, leading to a crash of the process. Users should upgrade to version 2.0.2 to receive a patch. No known workarounds are available.
- Published
- Jul 17, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.7% · 52th percentile
- CWE
- CWE-248
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
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.
Affected systems
—
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.
expressjs multer
- 1.4.4-lts.1 and later · before 2.0.2affected · 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 1.4.4-lts.1 · before 2.0.2 | 2.0.2 |
Same product
expressjs: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-3520Multer vulnerable to Denial of Service via uncontrolled recursion34Monitor
- CVE-2026-3304Multer vulnerable to Denial of Service via incomplete cleanup34Monitor
- CVE-2026-2359Multer vulnerable to Denial of Service via resource exhaustion34Monitor
- CVE-2025-48997Multer vulnerable to Denial of Service via unhandled exception34Monitor
- CVE-2026-82333multer vulnerable to Denial of Service via oversized array index in field names30Monitor
- CVE-2026-77078multer vulnerable to Denial of Service via crafted multipart field names30Monitor
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 |
|---|---|---|
| expressjs multer | 2.0.2 | Vendor (CNA) |
| npm:multer | 2.0.2 | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:0 | 2025-12-04 |
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.
- Published
- First PoC+139 d
- TodaySep 30, 2026+440 d
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.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2025-4899744 days apartMulter vulnerable to Denial of Service via unhandled exception34Monitor
- CVE-2025-4794459 days apartMulter vulnerable to Denial of Service from maliciously crafted requests30Monitor
- CVE-2026-77078407 days apartmulter vulnerable to Denial of Service via crafted multipart field names30Monitor
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-248 · Uncaught ExceptionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
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References
- cna.openjsf.org/security-advisories.html
- github.com/expressjs/multer/commit/adfeaf669f0e7fe953eab191a762164a452d143b
- github.com/expressjs/multer/security/advisories/GHSA-fjgf-rc76-4x9p
Vendor advisories and official records. Exploit/PoC links are deliberately left out.