Out-of-bounds read in NGINX ngx_http_charset_module
CVE-2026-42934 is an out-of-bounds read / heap buffer over-read vulnerability in NGINX Open Source and NGINX Plus within ngx_http_charset_module. The issue is described as an off-by-one error in UTF-8 handling when charset conversion is enabled, specifically involving charset, source_charset, charset_map, and proxy_pass with proxy buffering disabled (buffering "off"). Available reporting indicates the flaw can be triggered when incomplete UTF-8 sequences are processed across proxy buffer boundaries, causing incorrect length/state handling and a read past the end of a heap buffer in the NGINX worker process. The vulnerability is remotely reachable by an unauthenticated attacker via crafted requests, but only when the affected charset and proxy configuration combination is present.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
No valid public exploits. Mallory filtered out 3 candidates as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
Affected products & vendors
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Recent activity
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A medium-severity out-of-bounds read vulnerability in NGINX ngx_http_charset_module caused by an off-by-one error when handling incomplete UTF-8 sequences across proxy buffer boundaries.
An out-of-bounds read in NGINX ngx_http_charset_module that can expose memory contents or cause worker restart under a specific combination of charset and proxy buffering settings.
An out-of-bounds read vulnerability in NGINX ngx_http_charset_module that may allow memory disclosure or worker process restart when specific charset and proxy buffering configurations are present.
An off-by-one UTF-8 parsing vulnerability in NGINX that can cause out-of-bounds reads.
The version that knows your environment.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.