Memory disclosure and worker restart via upstream responses
Published May 13, 2026 · Updated May 13, 2026
Buffer over-read in F5 NGINX products allows man-in-the-middle attackers to read worker memory or restart a worker process. The SCGI and uWSGI response handlers process attacker-controlled upstream metadata without correctly bounding allocations and pointer offsets. Exploitation requires scgi_pass or uwsgi_pass and control of an upstream response; impact is limited to worker-memory disclosure or worker restart.
Summary
What happened
Buffer over-read in F5 NGINX products allows man-in-the-middle attackers to read worker memory or restart a worker process. The SCGI and uWSGI response handlers process attacker-controlled upstream metadata without correctly bounding allocations and pointer offsets. Exploitation requires scgi_pass or uwsgi_pass and control of an upstream response; impact is limited to worker-memory disclosure or worker restart.
The record
- CVE
- CVE-2026-42946
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- F5 Networks
- Product
- NGINX Open Source
- Classifications
- CWE-823, CWE-789, T1557
- 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?
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- Affected versionversion=0.8.42 <1.30.1
What conditions does exploitation require?
What is affected?
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
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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