Denial of service via mishandled epoll resets
Published May 13, 2026 · Updated May 13, 2026
Denial of service in Netty 4.2.0.Final through 4.2.12.Final allows remote attackers to exhaust server resources via crafted TCP resets. EpollIoHandler leaves a file descriptor registered with a zero event mask after a half-closed connection receives RST, so EPOLLHUP or EPOLLERR repeatedly wakes the event loop. Exploitation requires Linux epoll transport and half-closure through ALLOW_HALF_CLOSURE or the HTTP codec; repeated connections exhaust descriptors or spin an event-loop thread.
Summary
What happened
Denial of service in Netty 4.2.0.Final through 4.2.12.Final allows remote attackers to exhaust server resources via crafted TCP resets. EpollIoHandler leaves a file descriptor registered with a zero event mask after a half-closed connection receives RST, so EPOLLHUP or EPOLLERR repeatedly wakes the event loop. Exploitation requires Linux epoll transport and half-closure through ALLOW_HALF_CLOSURE or the HTTP codec; repeated connections exhaust descriptors or spin an event-loop thread.
The record
- CVE
- CVE-2026-42577
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- The Netty Project
- Product
- Netty
- Classifications
- CWE-772, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 13, 2026CVE publishedPublication date reported by the CVE source.
- May 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 4.2.0.Final, < 4.2.13.Final
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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