How severe is CVE-2026-42577?

CVE-2026-42577 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-42577 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42577?

CVE-2026-42577 affects Netty. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42577?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42577 have an EU (EUVD) identifier?

Yes. CVE-2026-42577 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30120.

When was CVE-2026-42577 published?

CVE-2026-42577 was published on 2026-05-13 and last updated on 2026-06-17.

CVE-2026-42577

CVE-2026-42577 is a high-severity vulnerability in Netty with a CVSS 3.x base score of 7.5. 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-772.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30120
Weakness: CWE-772
Affected product: Netty
Published: 2026-05-13
Last modified: 2026-06-17

Description

Netty is an asynchronous, event-driven network application framework. From 4.2.0.Final to 4.2.13.Final , Netty's epoll transport fails to detect and close TCP connections that receive a RST after being half-closed, leading to stale channels that are never cleaned up and, in some code paths, a 100% CPU busy-loop in the event loop thread. This vulnerability is fixed in 4.2.13.Final.

Frequently asked questions

What is CVE-2026-42577?: Netty is an asynchronous, event-driven network application framework. From 4.2.0.Final to 4.2.13.Final , Netty's epoll transport fails to detect and close TCP connections that receive a RST after being half-closed, leading to stale channels that are never cleaned up and, in some code paths, a 100% CPU busy-loop in the event loop thread. This vulnerability is fixed in 4.2.13.Final.
How severe is CVE-2026-42577?: CVE-2026-42577 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-42577 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42577?: CVE-2026-42577 affects Netty. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42577?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42577 have an EU (EUVD) identifier?: Yes. CVE-2026-42577 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30120.
When was CVE-2026-42577 published?: CVE-2026-42577 was published on 2026-05-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*

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