CVE-2020-13128: An issue was discovered in Manolo GWTUpload 1.0.3

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2020-13128 is a high-severity flaw (CVSS 7.5) affecting gwtupload. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Manolo GWTUpload 1.0.3. server/UploadServlet.java (the servlet for handling file upload) accepts a delay parameter that causes a thread to sleep. It can be abused to cause all of a server's threads to sleep, leading to denial of service.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-434
Published	2020-05-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: gwtupload project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-05-18 00:15 UTCPublished CVE record published
2026-06-17 02:52 UTCUpdated Record last modified

gwtupload project gwtupload DOWNGRADE

Affected: 1.0.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0.3

1. Check installed version

apt-cache policy gwtupload || rpm -q gwtupload || gwtupload --version

2. No fixed release: DOWNGRADE to a release before 1.0.3 (Debian / Ubuntu)

apt-cache madison gwtupload sudo apt install gwtupload=<VERSION_BEFORE_1.0.3> sudo apt-mark hold gwtupload

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gwtupload sudo dnf downgrade gwtupload-<VERSION_BEFORE_1.0.3> sudo dnf versionlock add gwtupload

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-13128?

gwtupload: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-13128 being exploited?

CVE-2020-13128 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-13128 affect?

CVE-2020-13128 affects gwtupload. Severity is high (CVSS 7.5). An issue was discovered in Manolo GWTUpload 1.0.3. server/UploadServlet.java (the servlet for handling file upload) accepts a delay parameter that causes a thread to sleep. It can be abused to cause all of a server's threads to sleep, leadi

How urgent is CVE-2020-13128?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

Related CVEs

CVE-2020-9447 MEDIUM 6.1 DOWNGRADE There is an XSS (cross-site scripting) vulnerability in GwtUpload 1.0.3 in the file upload functionality

References

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