---
title: "CVE-2026-77762: Apache Tomcat - Race Condition"
description: "Apache Tomcat 8.5.59 through 8.5.100, 9.0.39 through 9.0.121, 10.1.0-M1 through 10.1.59, and 11.0.0-M1 through 11.0.25 contain a race condition caused by improper synchronization in HTTP/2 request handling, letting attackers inject trailer fields into other HTTP/2 requests, exploit requires crafted HTTP/2 requests."
url: https://panop.io/threat-heartbeat/CVE-2026-77762/
---

# CVE-2026-77762 Apache Tomcat - Race Condition

Apache Tomcat 8.5.59 through 8.5.100, 9.0.39 through 9.0.121, 10.1.0-M1 through 10.1.59, and 11.0.0-M1 through 11.0.25 contain a race condition caused by improper synchronization in HTTP/2 request handling, letting attackers inject trailer fields into other HTTP/2 requests, exploit requires crafted HTTP/2 requests.

CVSS base score 8.1 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.36% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-77762)

## Details

Type

Race Condition

Impact

Data Tampering

CVSS vector

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

Published

23 September 2026

Updated

15 October 2026

Weakness

[CWE-362](https://cwe.mitre.org/data/definitions/362.html)

## Vendor fix

Upgrade to versions 11.0.26, 10.1.60, or 9.0.122 or later.

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-2026-77762](https://nvd.nist.gov/vuln/detail/CVE-2026-77762)
- [https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn](https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn)
- [http://www.openwall.com/lists/oss-security/2026/09/23/23](http://www.openwall.com/lists/oss-security/2026/09/23/23)

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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

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