What is CVE-2026-66257?

CVE-2026-66257 is a high-severity vulnerability in Apache Qpid Proton-J, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-08-05.

How severe is CVE-2026-66257?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Apache Qpid Proton-J

CVE-2026-66257

A pre-authentication attacker could leverage unbounded symbol value caching to cause resource exhaustion leading to denial of service. This issue affects Apache Qpid Proton-J: through 0.34.1. Users are recommended to upgrade to version 0.35.0, which fixes the issue.

EPSS: 0.004 (36.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Apache Qpid_proton-j
Apache Software Foundation Qpid Proton-j — versions 0

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

security@apache.org (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-66257?: CVE-2026-66257 is a high-severity vulnerability in Apache Qpid Proton-J, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-08-05.
How severe is CVE-2026-66257?: High severity. CVSS v3 base score is 7.5 out of 10.