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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-8720

30
FAUCET Score

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.

First published: Jun 25, 2026Last modified: Jun 25, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.9.0, < 5.9.2CPE matchmatch criteria
cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
>= 5.9.0, <= 5.9.1CPE match
cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

5.9MEDIUM

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
HIGH
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.11%
Probability of exploitation in next 30 days
EPSS Percentile
1.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0011 is in the 0th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

microsoft2026-Jun/CVE-2026-8720Moderate

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

Jun 9, 2026

References

github.com / wolfSSL/wolfssl/pull/10447
Issue TrackingPatch
wolfssl.com / docs/security-vulnerabilities
Vendor Advisory