How severe is CVE-2026-5466?

CVE-2026-5466 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-5466 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-5466?

CVE-2026-5466 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-5466?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-5466 have an EU (EUVD) identifier?

Yes. CVE-2026-5466 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21291.

When was CVE-2026-5466 published?

CVE-2026-5466 was published on 2026-04-10 and last updated on 2026-06-17.

CVE-2026-5466

CVE-2026-5466 is a high-severity vulnerability in Wolfssl with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 7.6
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21291
Weakness: CWE-347
Affected product: Wolfssl
Published: 2026-04-10
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-5466?: 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.
How severe is CVE-2026-5466?: CVE-2026-5466 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-5466 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-5466?: CVE-2026-5466 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-5466?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-5466 have an EU (EUVD) identifier?: Yes. CVE-2026-5466 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21291.
When was CVE-2026-5466 published?: CVE-2026-5466 was published on 2026-04-10 and last updated on 2026-06-17.

References

https://github.com/wolfssl/wolfssl/pull/10102

Affected products (1)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

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