CVE-2026-86252 h3 before 1.15.9 SSE Event Injection via Carriage Return

h3 versions before 1.15.9 fail to sanitize carriage return characters in EventStream data and comment fields, allowing attackers to inject arbitrary SSE events by including unsanitized carriage returns. Attackers can inject event type directives, split single push calls into multiple browser-pars...

CVE-2026-86252 h3 before 1.15.9 SSE Event Injection via Carriage Return

h3 versions before 1.15.9 fail to sanitize carriage return characters in EventStream data and comment fields, allowing attackers to inject arbitrary SSE events by including unsanitized carriage returns. Attackers can inject event type directives, split single push calls into multiple browser-pars...

CVE-2026-86250 h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie and deleteChunkedCookie functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an On² cleanup loop that hangs the server...

CVE-2026-86250 h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie and deleteChunkedCookie functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an On² cleanup loop that hangs the server...

CVE-2026-86251 h3 before 1.15.9 Path Traversal via Double Decoding

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences e.g. %252e%252e to be decoded to %2e%2e, which survives resolveDotSegments because that function only checks for litera...

CVE-2026-86251 h3 before 1.15.9 Path Traversal via Double Decoding

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences e.g. %252e%252e to be decoded to %2e%2e, which survives resolveDotSegments because that function only checks for litera...

EUVD-2026-72107

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences e.g. %252e%252e to be decoded to %2e%2e, which survives resolveDotSegments because that function only checks for litera...

CVE-2026-86251

Versions of h3 before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. The root cause is a double-decoding flaw : a request path containing double-encoded dot sequences (e.g. %252e%252e) decodes to %2e%2e, which survives the resolveDotSegments() function because it only c...

CVE-2026-86251 h3 before 1.15.9 Path Traversal via Double Decoding

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences e.g. %252e%252e to be decoded to %2e%2e, which survives resolveDotSegments because that function only checks for litera...

EUVD-2026-72106

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie and deleteChunkedCookie functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an On² cleanup loop that hangs the server...

CVE-2026-86250 h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie and deleteChunkedCookie functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an On² cleanup loop that hangs the server...

CVE-2026-86250

h3 versions before 2.0.1-rc.18 contain a denial-of-service vulnerability in the setChunkedCookie() and deleteChunkedCookie() functions. The library fails to validate the chunk count parsed from user-controlled cookie values, allowing a remote, unauthenticated attacker to send a crafted cookie hea...

EUVD-2026-72105

h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a...

CVE-2026-86205 h3 before 2.0.1-rc.18 Open Redirect via redirectBack()

h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a...

CVE-2026-86205

h3 versions before 2.0.1-rc.18 are affected by an open redirect vulnerability in the redirectBack() utility. The root cause is a failure to sanitize protocol-relative paths in the Referer header pathname: an attacker can craft a same-origin URL containing a double-slash path segment that passes o...

CVE-2026-86205 h3 before 2.0.1-rc.18 Open Redirect via redirectBack()

h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a...

CVE-2026-86205 h3 before 2.0.1-rc.18 Open Redirect via redirectBack()

h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a...

PT-2026-86518

h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a...

CVE-2026-86252: Improper Neutralization of Special Elements in Output Used by a Downstream Component

h3 versions before 1.15.9 fail to sanitize carriage return characters in EventStream data and comment fields, allowing attackers to inject arbitrary SSE events by including unsanitized carriage returns. Attackers can inject event type directives, split single push calls into multiple browser-pars...

CVE-2026-86251: Improper Limitation of a Pathname to a Restricted Directory

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences e.g. %252e%252e to be decoded to %2e%2e, which survives resolveDotSegments because that function only checks for litera...