CVE-2026-67591

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

MEDIUM
6.5
CVSS Score
Published: August 5, 2026 at 05:38 AM UTC
Updated: October 24, 2026 at 04:10 PM UTC
1 product affected across 1 vendorQpid PROTONJ2

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.2.0
Affected range stops below 1.2.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

Vendor AdvisoryMailing List
Source: cverecord
https://lists.apache.org/thread/rwmggh2bkm6qotxpdfcplht3jgw5n036
Mailing ListThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/08/04/30

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770

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