multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 2 fixed, 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.
Summary
multer is a middleware for handling multipart/form-data in Node.js. In version 2.2.0, when a disk-backed upload is aborted or truncated before the write stream finishes, multer's disk storage engine removes the visible file but does not close the underlying write file descriptor, leaving a deleted but still open descriptor. A remote attacker able to reach an upload route using the built-in disk storage can send repeated aborted or malformed multipart uploads, each one leaking a file descriptor and retaining disk blocks until the process exits, which can exhaust resources and cause a denial of service. The issue is fixed in multer 2.3.0, which closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed. Upgrade to multer 2.3.0 to remediate.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| expressjs | multer | 2.2.0 to before 2.3.0 | 2.3.0 | Patch available | CNA |
| — | multer (npm) | 2.2.0 to before 2.3.0 | 2.3.0 | Patch available | GHSA-qfvm-cv95-jqjf |
- multer Vendorexpressjs Affected 2.2.0 to before 2.3.0 Fixed in 2.3.0 Patch available CNA
- multer (npm) Vendor— Affected 2.2.0 to before 2.3.0 Fixed in 2.3.0 Patch available GHSA-qfvm-cv95-jqjf
Remediation
- Fix · CNA multer (multer) Fixed in 2.3.0
- Fix · GHSA-qfvm-cv95-jqjf multer (npm) Fixed in 2.3.0 Advisory →
Red Hat 4 advisories
- RHSA-2026:86675 Released 2026-10-21 · Red Hat rating ImportantAnsible plug-ins for Red Hat Developer Hub Product Release Update
- Red Hat Ansible Automation Platform 2.2 registry.redhat.io/ansible-automation-platform/automation-portal
- RHSA-2026:82151 Released 2026-10-13 · Red Hat rating CriticalAnsible automation portal Red Hat Enterprise Linux Images
- Red Hat Ansible Automation Platform 2.2 registry.redhat.io/ansible-automation-platform/bootc-automation-portal-rhel9
- RHSA-2026:79088 Released 2026-10-08 · Red Hat rating CriticalRed Hat Developer Hub 1.10.5 release.
- Red Hat Developer Hub 1.10 registry.redhat.io/rhdh/rhdh-hub-rhel9, registry.redhat.io/rhdh/rhdh-rhel9-operator
Show 1 more Red Hat advisories
- RHSA-2026:76788 Released 2026-10-06 · Red Hat rating CriticalRed Hat Developer Hub 1.10.5 Plugin Catalog GA plugins release.
- Red Hat Developer Hub 1.10 registry.redhat.io/rhdh/red-hat-developer-hub-backstage-plugin-lightspeed, registry.redhat.io/rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend, registry.redhat.io/rhdh/red-hat-developer-hub-backstage-plugin-orchestrator +4
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
multer 2.3.0
4 records Highest priority Priority LOW 4 LOW
Other records, highest priority first
- TI-2026-56780 multer vulnerable to Denial of Service via oversized array index in field namesPriority LOW 39
- TI-2026-53831 multer vulnerable to Denial of Service via crafted multipart field namesPriority LOW 39
- TI-2026-53818 multer vulnerable to file size limit bypass via async fileFilter race conditionPriority LOW 17
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Logging Subsystem for Red Hat OpenShift | Affected | No fix planned: Will not fix |
| Red Hat Developer Hub 1 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat Trusted Profile Analyzer | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2.2 | Fixed | RHSA-2026:82151, RHSA-2026:86675 |
| Red Hat Developer Hub 1.10 | Fixed | RHSA-2026:76788, RHSA-2026:79088 |
Not affected: 7 products
- Red Hat 3scale API Management Platform 2
- Red Hat Developer Hub 1.10
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-77037
- 2026-10-03 Alias added: GHSA-qfvm-cv95-jqjf
- 2026-10-07 Fix available: RHSA-2026:76788 · Red Hat
- 2026-10-07 Fix available: Red Hat Developer Hub 1.10 · Red Hat
- 2026-10-09 Fix available: RHSA-2026:79088 · Red Hat
- 2026-10-09 Affected versions changed · Red Hat
- 2026-10-13 Fix available: Red Hat Ansible Automation Platform 2.2 · Red Hat
- 2026-10-13 Fix available: RHSA-2026:82151 · Red Hat
- 2026-10-21 Fix available: RHSA-2026:86675 · Red Hat
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-26 Affected versions changed · Red Hat
- 2026-10-27 Affected versions changed · Red Hat
References
Advisory 3
More expressjs Multer vulnerabilities
- TI-2026-03033 Multer vulnerable to Denial of Service via uncontrolled recursion CVSS 4.0HIGH 8.7
- TI-2026-02853 Multer vulnerable to Denial of Service via incomplete cleanup CVSS 4.0HIGH 8.7
- TI-2026-01995 Multer vulnerable to Denial of Service via resource exhaustion CVSS 4.0HIGH 8.7
- TI-2026-56780 multer vulnerable to Denial of Service via oversized array index in field names CVSS 3.1HIGH 7.5
- TI-2026-53831 multer vulnerable to Denial of Service via crafted multipart field names CVSS 3.1HIGH 7.5
- TI-2026-04434 multer vulnerable to Denial of Service via deeply nested field names CVSS 3.1HIGH 7.5
Sources
- CVE-2026-77037 · CVE Program
- CVE-2026-77037 · NVD
- FIRST EPSS
- GHSA-qfvm-cv95-jqjf · GitHub Advisory Database · CC BY 4.0
- CVE-2026-77037 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences