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Ubuntu 25.10 nghttp2 Critical Denial of Service USN-8233-1

ubuntu
Calendar Grey May 5, 2026
Dist Ubuntu Esm H88
Critical nghttp2 flaw allows denial of service with crafted traffic. Update Ubuntu systems to mitigate risks.
nghttp2 could be made to crash if it received specially crafted network traffic.

Summary

nghttp2 could be made to crash if it received specially crafted

network traffic.

Software Description:

- nghttp2: HTTP/2 C Library and tools

Details:

Andrew MacPherson discovered that nghttp2 did not properly validate

internal state when the session termination API was called. A remote

attacker could possibly use this issue to cause nghttp2 to crash, resulting

in a denial of service.

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu nghttp2

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 25.10
  libnghttp2-14                   1.64.0-1.1ubuntu1.1
  nghttp2                         1.64.0-1.1ubuntu1.1

Ubuntu 24.04 LTS
  libnghttp2-14                   1.59.0-1ubuntu0.3
  nghttp2                         1.59.0-1ubuntu0.3

Ubuntu 22.04 LTS
  libnghttp2-14                   1.43.0-1ubuntu0.3
  nghttp2                         1.43.0-1ubuntu0.3

Ubuntu 20.04 LTS
  libnghttp2-14                   1.40.0-1ubuntu0.3+esm1
                                  Available with Ubuntu Pro
  nghttp2                         1.40.0-1ubuntu0.3+esm1
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libnghttp2-14                   1.30.0-1ubuntu1+esm3
                                  Available with Ubuntu Pro
  nghttp2                         1.30.0-1ubuntu1+esm3
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  libnghttp2-14                   1.7.1-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro
  nghttp2                         1.7.1-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary
changes.

References

https://ubuntu.com/security/notices/USN-8233-1

CVE-2026-27135

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8233-1

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu nghttp2

Package Information

https://launchpad.net/ubuntu/+source/nghttp2/1.64.0-1.1ubuntu1.1
https://launchpad.net/ubuntu/+source/nghttp2/1.59.0-1ubuntu0.3
https://launchpad.net/ubuntu/+source/nghttp2/1.43.0-1ubuntu0.3

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