CVE-2023-1973 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in undertow. A fix is available for undertow — see the affected versions and patch details below.
Undertow Denial of Service vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-1973.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
undertowReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Debian:13 packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in Undertow package. Using the FormAuthenticationMechanism, a malicious user could trigger a Denial of Service by sending crafted requests, leading the server to an OutofMemory error, exhausting the server's memory.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦Debian:13 | undertow | all versions | 2.3.18-1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undertow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update undertow to 2.3.18-1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-1973 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 | eap7-activemq-artemis-0:1.5.5.016-1.redhat_00001.1.ep7.el7 | RHSA-2025:4226 |
| Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 | eap7-jackson-annotations-0:2.10.4-3.redhat_00006.1.el7eap | RHSA-2025:9583 |
| Red Hat JBoss Enterprise Application Platform 7.4.16 | io.undertow/undertow-core:2.2.30.SP1-redhat-00001 | RHSA-2024:1677 |
| Red Hat JBoss Enterprise Application Platform 7.4 for RHEL 8 | eap7-undertow-0:2.2.30-1.SP1_redhat_00001.1.el8eap | RHSA-2024:1675 |
| Red Hat JBoss Enterprise Application Platform 7.4 for RHEL 9 | eap7-undertow-0:2.2.30-1.SP1_redhat_00001.1.el9eap | RHSA-2024:1676 |
| Red Hat JBoss Enterprise Application Platform 7.4 on RHEL 7 | eap7-undertow-0:2.2.30-1.SP1_redhat_00001.1.el7eap | RHSA-2024:1674 |
| Red Hat JBoss Enterprise Application Platform 8 | undertow-core | RHSA-2024:2763 |
| Red Hat JBoss Enterprise Application Platform 8.0 for RHEL 8 | eap8-undertow-0:2.3.11-1.SP1_redhat_00001.1.el8eap | RHSA-2024:2764 |
Frequently Asked Questions
Is CVE-2023-1973 in your dependencies?
Find it across Debian:13, including transitive dependencies.