High severity · published Mar 4, 2026
CVE-2026-3520
Multer vulnerable to Denial of Service via uncontrolled recursion
7.5
CVSS
0.7%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 54% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MU
multer · expressjs
before 2.1.1 · source: vendor, NVD
RH
Red Hat Developer Hub 1.8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Developer Hub 1.9 · Red Hat
All versions, or not specified · source: CISA
SA
Self-service automation portal 2 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-3520
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-3520
Third Party Advisory
https://cna.openjsf.org/security-advisories.html
Patch
https://github.com/expressjs/multer/commit/7e66481f8b2e6c54b982b34c152479e096ce2752
Vendor Advisory
https://github.com/expressjs/multer/security/advisories/GHSA-5528-5vmv-3xc2
Third Party Advisory
https://www.cve.org/CVERecord?id=CVE-2026-3520
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:6174
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:6802
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