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CVE-2026-3547

HIGH CVSS 3.1: 7.5 EPSS 0.05%
Updated Mar 26, 2026
Nginx
Parameter Value
CVSS 7.5 (HIGH)
Affected Versions before 5.9.0
Fixed In 5.9.0
Type CWE-125 (Out-of-bounds Read)
Vendor Nginx
Public PoC No

Out-of-bounds read in ALPN parsing due to incomplete validation. wolfSSL 5.8.4 and earlier contained an out-of-bounds read in ALPN handling when built with ALPN enabled (HAVE_ALPN / --enable-alpn). A crafted ALPN protocol list could trigger an out-of-bounds read, leading to a potential process crash (denial of service). Note that ALPN is disabled by default, but is enabled for these 3rd party compatibility features: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Wolfssl Wolfssl
cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
5.9.0