CVE-2026-5500 Improper Validation of AES-GCM Authentication Tag Length in PKCS#7 Envelope Allows Authentication Bypass

What is CVE-2026-5500?

CVE-2026-5500 is a high-severity vulnerability in Wolfssl Wolfssl, published on 10 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

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.

Weakness: CWE-20

Which versions are affected by CVE-2026-5500?

It affects 1 product.

Products include Wolfssl Wolfssl.

How do I fix CVE-2026-5500?

Apply the vendor's patch.

Is CVE-2026-5500 being exploited?

There is no known exploitation of CVE-2026-5500 in the wild and no public exploit code.

Other vulnerabilities in Wolfssl Wolfssl

• CVE-2024-5991 Buffer overread in domain name matching Critical 10.0
• CVE-2021-37155 Security feature bypass in n/a Critical 9.8
• CVE-2020-36177 Memory corruption in n/a Critical 9.8
• CVE-2014-2896 Memory corruption in n/a Critical 9.8
• CVE-2014-2897 Memory corruption in n/a Critical 9.8

All Wolfssl Wolfssl vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-5500, GHSA-m77r-vqw2-hffx, JLSEC-2026-729, UBUNTU-CVE-2026-5500.