Multer is a node.js middleware for handling multipart/form-data. A vulnerability in Multer prior to version 2.1.1 allows an attacker to trigger a Denial of Service (DoS) by sending malformed requests, potentially causing stack overflow. Users should upgrade to version 2.1.1 to receive a patch. No known workarounds are available.
CVE-2026-3520
HIGHNVD 7.57.5
EchelonGraph scoreLOW confidence
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(low)
- EPSS
- 49.2%
- KEV
- Not listed
Published
March 4, 2026
Last Modified
June 30, 2026
Advisory Details (9)
Auto-updated Jul 3, 2026Patch available. Sources: github_commit, github, redhat.
redhat Patch Available
redhat
2444584 – (CVE-2026-3520) CVE-2026-3520 multer: Multer: Denial of Service via malformed requests
https://bugzilla.redhat.com/show_bug.cgi?id=2444584redhat Patch Available
redhat Patch Available
github Patch Available
Multer vulnerable to Denial of Service via uncontrolled recursion · Advisory · expressjs/multer · GitHub
https://github.com/expressjs/multer/security/advisories/GHSA-5528-5vmv-3xc2github_commit Patch Available
commit 7e66481f8b2e (expressjs/multer)
Patch available: expressjs/multer v2.1.1 (contains commit 7e66481f8b2e)
https://github.com/expressjs/multer/commit/7e66481f8b2e6c54b982b34c152479e096ce2752generic
Security Advisories | OpenJS Foundation CVE Numbering Authority
https://cna.openjsf.org/security-advisories.htmlVendor Advisories for CVE-2026-3520(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Patch Availability(2)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| redhat | rhdh/rhdh-hub-rhel9:1775140647 | 2026-04-07 | redhat |
| redhat | rhdh/rhdh-hub-rhel9:1774545605 | 2026-03-30 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| multer | — | 2.1.1 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 11× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-05 02:30 UTCEPSS rescore
- 2026-07-04 06:31 UTCEPSS rescore
- 2026-07-01 15:06 UTCEPSS rescore
- 2026-06-30 23:22 UTCEPSS rescore
- 2026-06-30 04:35 UTCEG score recompute
- 2026-06-30 04:35 UTCVendor advisory
- 2026-06-30 04:31 UTCNVD updatefirst tracked
Related CVEs(same vendor + same CWE)
Same vendor
10 shownredhat
Frequently asked(5)
What is CVE-2026-3520?
CVE-2026-3520 is a high vulnerability published on March 4, 2026. Multer is a node.js middleware for handling multipart/form-data. A vulnerability in Multer prior to version 2.1.1 allows an attacker to trigger a Denial of Service (DoS) by sending malformed requests, potentially causing stack overflow. Users should upgrade to version 2.1.1 to receive a patch. No…
When was CVE-2026-3520 disclosed?
CVE-2026-3520 was first published in the National Vulnerability Database on March 4, 2026, with the most recent update on June 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3520 actively exploited?
CVE-2026-3520 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 49.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-3520?
CVE-2026-3520 has a CVSS v3 base score of 7.5 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-3520?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3520, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-3520
Is Your Infrastructure Affected by CVE-2026-3520?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.