What is CVE-2026-67591?

CVE-2026-67591 is a medium-severity vulnerability in Apache Qpid Protonj2, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-08-05.

How severe is CVE-2026-67591?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Resource exhaustion in Apache Qpid Protonj2

CVE-2026-67591

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.

Published 2026-08-05 · last modified 2026-10-24.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.007 (51.3th percentile), scored 2026-11-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Apache Qpid Protonj2
Apache Software Foundation Qpid Protonj2 — versions 0

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

lists.apache.org/thread/rwmggh2bkm6qotxpdfcplht3jgw5n036 (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-67591?: CVE-2026-67591 is a medium-severity vulnerability in Apache Qpid Protonj2, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-08-05.
How severe is CVE-2026-67591?: Medium severity. CVSS v3 base score is 6.5 out of 10.