---
title: "CVE-2026-78437: Apache Tomcat - Denial of Service"
description: "Apache Tomcat 11.0.19 through 11.0.25, 10.1.53 through 10.1.59, and 9.0.116 through 9.0.121 contain an incomplete cleanup vulnerability caused by malformed requests, letting attackers cause requests from other users to fail, exploit requires timing conditions."
url: https://panop.io/threat-heartbeat/CVE-2026-78437/
---

# CVE-2026-78437 Apache Tomcat - Denial of Service

Apache Tomcat 11.0.19 through 11.0.25, 10.1.53 through 10.1.59, and 9.0.116 through 9.0.121 contain an incomplete cleanup vulnerability caused by malformed requests, letting attackers cause requests from other users to fail, exploit requires timing conditions.

CVSS base score 7.3 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.26% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-78437)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Published

23 September 2026

Updated

15 October 2026

Weakness

[CWE-459](https://cwe.mitre.org/data/definitions/459.html)

## Vendor fix

Upgrade to version 11.0.26, 10.1.60, or 9.0.122.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-78437](https://nvd.nist.gov/vuln/detail/CVE-2026-78437)
- [https://lists.apache.org/thread/qkmsos3s8chn5053qr466rzwv6sk5gjg](https://lists.apache.org/thread/qkmsos3s8chn5053qr466rzwv6sk5gjg)
- [http://www.openwall.com/lists/oss-security/2026/09/23/26](http://www.openwall.com/lists/oss-security/2026/09/23/26)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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