Vulnerability · Published Aug 5, 2026 · Assigned by apache
CVE-2026-67591Apache Qpid ProtonJ2: Incoming session flow control window can be exceeded
Medium 6.5
In plain English
A medium-severity resource allocation without limits in Apache Qpid ProtonJ2 from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 51% of all known vulnerabilities).
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.7%top 48.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | qpid-proton | no fix listed | DEBIAN-CVE-2026-67591 |
| Debian:13 | qpid-proton | no fix listed | DEBIAN-CVE-2026-67591 |
| Debian:14 | qpid-proton | no fix listed | DEBIAN-CVE-2026-67591 |
| Ubuntu:22.04:LTS | qpid-proton | no fix listed | UBUNTU-CVE-2026-67591 |
| Ubuntu:24.04:LTS | qpid-proton | no fix listed | UBUNTU-CVE-2026-67591 |
| Ubuntu:26.04:LTS | qpid-proton | no fix listed | UBUNTU-CVE-2026-67591 |
| Ubuntu:26.10 | qpid-proton | no fix listed | UBUNTU-CVE-2026-67591 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache Qpid ProtonJ2 | 0 – through 1.1.0 |
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H