Vulnerability · Published Mar 19, 2026 · Assigned by wolfSSL
CVE-2026-3547wolfSSL: out-of-bounds read (DoS) in ALPN parsing due to incomplete validation
High 7.5
In plain English
A high-severity out-of-bounds read in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | wolfssl | 5.9.1-r0 | ALPINE-CVE-2026-3547 |
| Alpine:v3.24 | wolfssl | 5.9.0-r0 | ALPINE-CVE-2026-3547 |
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2026-3547 |
| Debian:13 | wolfssl | no fix listed | DEBIAN-CVE-2026-3547 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-3547 |
| Ubuntu:24.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-3547 |
| Ubuntu:25.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-3547 |
| Ubuntu:26.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-3547 |
| Ubuntu:26.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-3547 |
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H