CVE-2026-5038 multer vulnerable to Denial of Service via incomplete cleanup of aborted uploads
An attacker can exhaust disk space by triggering aborted uploads, causing denial of service in applications using multer with diskStorage.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-5038?
CVE-2026-5038 is a medium-severity denial of service vulnerability in multer, published on 15 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Impact: multer versions 2.0.0-alpha.1 through 2.1.1 and 3.0.0-alpha.1 are vulnerable to a Denial of Service when using diskStorage. Aborted or malformed multipart uploads leave orphaned partial files on disk because the Readable.pipe() call does not propagate the stream destroy signal to the underlying fs.WriteStream. An attacker can exhaust disk space by triggering many aborted uploads, with no application bug required.
Patches: Users should upgrade to multer 2.2.0 (2.x line) or 3.0.0-alpha.2 (3.x prerelease). Both versions track in-flight write streams and clean them up on the abort path.
Workarounds: None.
Weakness: CWE-459
Which versions are affected by CVE-2026-5038?
4 open source packages ship an affected version, including multer. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
multer npm | From 2.0.0-alpha.1 | 2.2.0 |
multer npm | From 2.0.0-alpha.1 | 2.2.0 |
multer npm | From 3.0.0-alpha.1 | 3.0.0-alpha.2 |
multer npm | From 3.0.0-alpha.1 | 3.0.0-alpha.2 |
Products include Expressjs Multer.
How do I fix CVE-2026-5038?
Upgrade multer to a fixed version for your release line: 2.2.0 or 3.0.0-alpha.2.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-5038 being exploited?
There is no known exploitation of CVE-2026-5038 in the wild and no public exploit code.
Other vulnerabilities in multer
- CVE-2026-3520 Multer vulnerable to Denial of Service via uncontrolled recursion
- CVE-2026-2359 Multer vulnerable to Denial of Service via resource exhaustion
- CVE-2026-3304 Multer vulnerable to Denial of Service via incomplete cleanup
- CVE-2026-77037 multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
- CVE-2026-77078 multer vulnerable to Denial of Service via crafted multipart field names
Sources
Also known as ECHO-5e3d-8f6c-d17d, GHSA-3p4h-7m6x-2hcm, MINI-4cjj-qmf8-6c6j, ROOT-APP-NPM-CVE-2026-5038.