Vulnerability · Published Apr 10, 2026 · Assigned by wolfSSL
CVE-2026-5500Improper Validation of AES-GCM Authentication Tag Length in PKCS#7 Envelope Allows Authentication Bypass
High 8.7
In plain English
A high-severity improper input validation 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 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)8.7High
Exploit odds (30 days)0.5%top 58.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
wolfSSL's wc_PKCS7_DecodeAuthEnvelopedData() does not properly sanitize the AES-GCM authentication tag length received and has no lower bounds check. A man-in-the-middle can therefore truncate the mac field from 16 bytes to 1 byte, reducing the tag check from 2⁻¹²⁸ to 2⁻⁸.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | wolfssl | 5.9.1-r0 | ALPINE-CVE-2026-5500 |
| Alpine:v3.24 | wolfssl | 5.9.1-r0 | ALPINE-CVE-2026-5500 |
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2026-5500 |
| Debian:13 | wolfssl | no fix listed | DEBIAN-CVE-2026-5500 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-5500 |
| Ubuntu:24.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-5500 |
| Ubuntu:25.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-5500 |
| Ubuntu:26.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-5500 |
| Ubuntu:26.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-5500 |
Affected products (as reported)
Weakness: CWE-20 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N