CVE-2026-67591

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

Published Aug 5, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

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.

Analysis

Technical impact

The vulnerability allows an authenticated attacker to exceed the session flow control incoming window in Apache Qpid ProtonJ2, leading to resource exhaustion and denial of service. It is classified as a Capacity Overflow (CWE-770).

Affected Systems

Systems running Apache Qpid ProtonJ2 up to and including version 1.1.0 are impacted. The product is maintained by the Apache Software Foundation and it is inferred that any Java application embedding ProtonJ2 may be affected.

Risk and Exploitability

Because authentication is required, the likely attack vector involves an authenticated network channel or local access with valid credentials. The CVSS score is 6.5 and the EPSS score is < 1%, and the vulnerability is not listed in the CISA KEV catalog. Applying the upgrade to 1.2.0 removes the risk.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Apache Software Foundation

Apache Qpid ProtonJ2

unaffected

Version	Status	Constraints
`0`	affected	≤ 1.1.0

Configuration 1 [-]

cpe:2.3:a:apache:qpid_protonj2:*:*:*:*:*:*:*:*

No data.

Vendor Product Versions

Apache

Qpid Proton-j

Version	Status	Scheme	Platform
`[0,1.1.0]`	affected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the ProtonJ2 library to version 1.2.0 or later in all affected deployments.
Restrict authentication to trusted roles and audit credentials to reduce the attack surface.
Enforce network segmentation so that only internal trusted services can communicate with ProtonJ2 endpoints.

Generated by OpenCVE AI on August 6, 2026 at 17:29 UTC.

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.653% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
http://www.openwall.com/lists/oss-security/2026/08/04/30
https://lists.apache.org/thread/rwmggh2bkm6qotxpdfcplht3jgw5n036

History

Aug 11, 2026 2:30 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Apache qpid Proton-j
Vendors & Products		Apache qpid Proton-j

Aug 6, 2026 4:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}` ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Aug 5, 2026 6:30 AM Description updated. Title updated. Weaknesses updated. Added references View changes

Type	Values Removed	Values Added
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.
Title		Apache Qpid ProtonJ2: Incoming session flow control window can be exceeded
Weaknesses		CWE-770
References		https://lists.apache.org/thread/rwmggh2bkm6qotxpdfcplht3jgw5n036