How severe is CVE-2026-67591?

CVE-2026-67591 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-67591 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-67591?

CVE-2026-67591 affects Apache Qpid Protonj2. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-67591?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-67591 published?

CVE-2026-67591 was published on 2026-08-05 and last updated on 2026-08-07.

CVE-2026-67591

CVE-2026-67591 is a medium-severity vulnerability in Apache Qpid Protonj2 with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Apache Qpid Protonj2
Published: 2026-08-05
Last modified: 2026-08-07

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-67591?: CVE-2026-67591 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-67591 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-67591?: CVE-2026-67591 affects Apache Qpid Protonj2. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-67591?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-67591 published?: CVE-2026-67591 was published on 2026-08-05 and last updated on 2026-08-07.

References

Affected products (1)

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

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