expressjs multer up to 2.1.0 recursion

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3$0-$5k0.00

Summaryinfo

A vulnerability was found in expressjs multer up to 2.1.0. It has been rated as problematic. The affected element is an unknown function. The manipulation leads to recursion. This vulnerability is documented as CVE-2026-3520. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in expressjs multer up to 2.1.0. This issue affects an unknown function. The manipulation with an unknown input leads to a recursion vulnerability. Using CWE to declare the problem leads to CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Impacted is availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-3520 since 03/04/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 2.1.1 eliminates this vulnerability. Applying the patch 7e66481f8b2e6c54b982b34c152479e096ce2752 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0903). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • IBM App Connect Enterprise

Productinfo

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Recursion
CWE: CWE-674 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: multer 2.1.1
Patch: 7e66481f8b2e6c54b982b34c152479e096ce2752

Timelineinfo

03/04/2026 Advisory disclosed
03/04/2026 +0 days CVE reserved
03/04/2026 +0 days VulDB entry created
03/31/2026 +27 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-5528-5vmv-3xc2
Status: Confirmed

CVE: CVE-2026-3520 (🔒)
GCVE (CVE): GCVE-0-2026-3520
GCVE (VulDB): GCVE-100-348761
CERT Bund: WID-SEC-2026-0903 - IBM App Connect Enterprise: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 03/04/2026 18:35
Updated: 03/31/2026 02:19
Changes: 03/04/2026 18:35 (68), 03/06/2026 15:56 (1), 03/10/2026 03:05 (11), 03/31/2026 02:19 (7)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Want to know what is going to be exploited?

We predict KEV entries!