CVE-2026-67553 Apache Qpid Proton Dotnet: Incoming session flow control window can be exceeded

What is CVE-2026-67553?

CVE-2026-67553 is a medium-severity denial of service vulnerability in Apache Qpid Proton Dotnet, published on 5 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

An authenticated attacker could exceed the session flow control incoming window potentially leading to denial of service.

This issue affects Apache Qpid Proton-Dotnet: through 1.0.0.

Users are recommended to upgrade to version 1.1.0, which fixes the issue.

Weakness: CWE-770

Which versions are affected by CVE-2026-67553?

It affects 1 product.

Products include Apache Qpid Proton-Dotnet.

How do I fix CVE-2026-67553?

No fix has been published for CVE-2026-67553 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-67553 being exploited?

There is no known exploitation of CVE-2026-67553 in the wild and no public exploit code.

Other vulnerabilities in Apache Qpid Proton Dotnet

• CVE-2026-67465 Apache Qpid Proton Dotnet: Unbounded symbol value caching can lead to pre-authentication resource exhaustion High 7.5
• CVE-2026-67551 Apache Qpid Proton Dotnet: Type size/count handling can lead to excessive allocation pre-authentication High 7.5
• CVE-2026-67552 Apache Qpid Proton Dotnet: Unbounded type nesting can lead to pre-authentication stackoverflow High 7.5
• CVE-2026-67554 Apache Qpid Proton Dotnet: Unbounded disposition range handling can lead to denial of service Medium 6.5
• CVE-2026-67555 Apache Qpid Proton Dotnet: Unable to govern the maximum number of transfer frames per incoming delivery Medium 6.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-rxxp-x2qg-g2f2.