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fix: whitelist safe characters in trailing-slash rewrite to prevent open redirect #2362

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B4nan wants to merge 2 commits into from
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fix: whitelist safe characters in trailing-slash rewrite to prevent open redirect #2362

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cd19142
fix: use map with \x5c hex escape to detect backslash in URI
B4nan Mar 23, 2026
ba9e960
fix: whitelist safe characters in trailing-slash rewrite regex
B4nan Mar 23, 2026
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9 changes: 5 additions & 4 deletions nginx.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -36,10 +36,11 @@ server {

# remove trailing slashes from all URLs (except root /)
# exact match locations (e.g., location = /sdk/js/) take priority over this regex
# [^\\\\] excludes backslashes to prevent open redirect: nginx decodes %5C to \ in $uri,
# and \ in the Location header gets normalized to / by browsers, turning /\evil.com
# into the protocol-relative URL //evil.com which redirects to evil.com.
location ~ ^([^\\\\]+)/$ {
# Only match URIs composed of safe characters (letters, digits, dots, hyphens,
# underscores, forward slashes). This prevents open redirect via %5C (backslash):
# nginx decodes %5C to \ in $uri, and \ in the Location header gets normalized
# to / by browsers, turning /\evil.com into //evil.com (protocol-relative URL).
location ~ ^(/[a-zA-Z0-9][a-zA-Z0-9_./-]*)/$ {
rewrite ^(.+)/$ $1$is_args$args? redirect;
}

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