CVE-2026-8720

HIGH

HMAC-BLAKE2 final discards message when key length exceeds block size

Title source: cna
STIX 2.1

Description

wc_Blake2bHmacFinal and wc_Blake2sHmacFinal discard the message when the key length exceeds the block size, producing a MAC that is independent of the input. When the supplied key is longer than the BLAKE2 block size the key-hashing branch reinitialized the running hash state, discarding the accumulated message data, so the resulting MAC depended only on the key and not on the message being authenticated. This bug is specific to the HMAC-BLAKE2 APIs that were added in wolfSSL version 5.9.0.

References (2)

Core 2

Scores

CVSS v3 7.5
EPSS 0.0011
EPSS Percentile 1.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-354
Status published
Products (2)
wolfSSL/wolfSSL 5.9.0 - 5.9.1
wolfssl/wolfssl 5.9.0 - 5.9.2
Published Jun 25, 2026
Tracked Since Jun 26, 2026