Incomplete Cleanup Affecting org.apache.tomcat.embed:tomcat-embed-core package, versions [9.0.116,9.0.122)[10.1.53,10.1.60)[11.0.19,11.0.26)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published26 Oct 2026
- disclosed23 Sept 2026
- creditUnknown
Introduced: 23 Sep 2026
CVE-2026-78437 (opens in a new tab)How to fix?
Upgrade org.apache.tomcat.embed:tomcat-embed-core to version 9.0.122, 10.1.60, 11.0.26 or higher.
Overview
org.apache.tomcat.embed:tomcat-embed-core is a Core Tomcat implementation.
Affected versions of this package are vulnerable to Incomplete Cleanup via the StreamProcessor request-recycling path in the HTTP/2 connector. An attacker can cause one request from another user to fail by sending a malformed HTTP/2 request that sets the per-request NOTE_BAD_REQUEST marker; because the marker is not cleared when the request is recycled and is only cleared during bad-request validation, it can persist into a reused request, depending on timing.
Notes
- The malformed-request entry point is an incorrectly formatted HTTP/2
:authorityorhostheader; other malformed requests are not identified as setting this bad-request marker.