Is CVE-2026-5466 in the CISA KEV catalog?

No. CVE-2026-5466 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-5466?

CVE-2026-5466 has a CVSS v3 base score of 8.1 (Important).

What is the EPSS score for CVE-2026-5466?

CVE-2026-5466 has an EPSS score of 0.15% (4th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-5466?

Upgrade wolfssl on debian unstable to 5.9.1-0.1 or later.

CVE & CISA-KEV Catalog

CVE-2026-5466

HIGH

8.1

CVSS v3

NVD

Description

wolfSSL's ECCSI signature verifier `wc_VerifyEccsiHash` decodes the `r` and `s` scalars from the signature blob via `mp_read_unsigned_bin` with no check that they lie in `[1, q-1]`. A crafted forged signature could verify against any message for any identity, using only publicly-known constants.

CWE-347

How to fix

Remediation Available

wolfsslDebian

Fixed in:5.9.1-0.1CVE-2026-5466

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploit Intelligence

0.15%probability of exploitation in 30 days

4thpercentile

Low risk: more likely to be exploited than 4% of all known CVEs.

References

Issue Tracking1

github.com

Related Vulnerabilities

Other CWE-347 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2018-16042	Medium	6.5	82%	-	-
CVE-2025-59718	Critical	9.8	66%	KEV	Fix
CVE-2025-25292	Critical	9.8	64%	-	Fix
CVE-2021-22160	Critical	9.8	53%	-	Fix
CVE-2013-3900	Medium	5.5	45%	KEV	-
CVE-2018-0114	High	7.5	43%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-29.