Apache Qpid ProtonJ2: Incoming session flow control window can be exceeded

published 2026-08-05 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-53089

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 51%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

apache qpid_protonj2 1.2.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-67591 updated 2026-08-25 cvss 6.5

Apache Qpid ProtonJ2: Apache Qpid ProtonJ2: Denial of Service via exceeding session flow control window

Red Hat AMQ Broker 7 protonj2-parent, protonj2-test-driver
affected: workaround, no fix available “Ensure authenticated access to AMQP endpoints is restricted to trusted clients to limit exposure to this DoS vulnerability.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 3 mo ago (2026-08-06)

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Apache Software Foundation Apache Qpid ProtonJ2

Classification

Weakness

CWE-770 Allocation of Resources Without Limits or Throttling

References

lists.apache.org /thread/rwmggh2bkm6qotxpdfcplht3jgw5n036
vendor-advisory, mailing-list
openwall.com /lists/oss-security/2026/08/04/30
mailing-list, third-party-advisory

Sources

CVE List CVE-2026-67591
NVD CVE-2026-67591

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary