CVE-2026-3520
Multer Vulnerable to Denial of Service via Uncontrolled Recursion
Description
### Impact A vulnerability in Multer versions < 2.1.1 allows an attacker to trigger a Denial of Service (DoS) by sending malformed requests, potentially causing stack overflow. ### Patches Users should upgrade to `2.1.1` ### Workarounds None ### Resources - https://github.com/expressjs/multer/security/advisories/GHSA-5528-5vmv-3xc2 - https://www.cve.org/CVERecord?id=CVE-2026-3520 - https://github.com/expressjs/multer/commit/7e66481f8b2e6c54b982b34c152479e096ce2752 - https://cna.openjsf.org/security-advisories.html
How to fix CVE-2026-3520
To remediate CVE-2026-3520, upgrade the affected package to a fixed version below.
- —upgrade to 2.1.1 or later
Is CVE-2026-3520 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 2.1.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |