Memory disclosure or worker restart via charset conversion
Published May 13, 2026 · Updated May 13, 2026
Heap buffer over-read in F5 NGINX Plus and NGINX Open Source allows remote attackers to disclose limited memory or restart workers. The ngx_http_charset_module response filter reads past a heap buffer while transcoding proxied response data when charset, source_charset, charset_map, and proxy_pass with proxy_buffering off are combined. Exploitation requires that non-default configuration and request-dependent conditions outside attacker control; impact is limited to memory fragments or a worker restart.
Summary
What happened
Heap buffer over-read in F5 NGINX Plus and NGINX Open Source allows remote attackers to disclose limited memory or restart workers. The ngx_http_charset_module response filter reads past a heap buffer while transcoding proxied response data when charset, source_charset, charset_map, and proxy_pass with proxy_buffering off are combined. Exploitation requires that non-default configuration and request-dependent conditions outside attacker control; impact is limited to memory fragments or a worker restart.
The record
- CVE
- CVE-2026-42934
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- F5 Networks
- Product
- NGINX Open Source
- Classifications
- CWE-125, T1499, T1190
- 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=0.3.50 <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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