CVE-2026-67591 Apache Qpid ProtonJ2: Incoming session flow control window can be exceeded
An authenticated attacker can exceed session flow control windows in Apache Qpid ProtonJ2, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-67591?
CVE-2026-67591 is a medium-severity denial of service vulnerability in Apache Qpid ProtonJ2, 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 ProtonJ2: through 1.1.0.
Users are recommended to upgrade to version 1.2.0, which fixes the issue.
Weakness: CWE-770
Which versions are affected by CVE-2026-67591?
It affects 1 product.
Products include Apache Qpid Protonj2.
How do I fix CVE-2026-67591?
No fix has been published for CVE-2026-67591 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-2026-67591 being exploited?
There is no known exploitation of CVE-2026-67591 in the wild and no public exploit code.
Other vulnerabilities in Apache Qpid ProtonJ2
- CVE-2026-67588 Apache Qpid ProtonJ2: Unbounded symbol value caching can lead to pre-authentication resource exhaustion
- CVE-2026-67589 Apache Qpid ProtonJ2: Type size/count handling can lead to excessive allocation pre-authentication
- CVE-2026-67590 Apache Qpid ProtonJ2: Unbounded type nesting can lead to pre-authentication stackoverflow
- CVE-2026-67592 Apache Qpid ProtonJ2: Unable to govern the maximum number of transfer frames per incoming delivery
Sources
Also known as GHSA-xcxh-hgpq-crj6, UBUNTU-CVE-2026-67591.