How severe is CVE-2026-3549?

CVE-2026-3549 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-3549 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-3549?

CVE-2026-3549 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-3549?

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

Does CVE-2026-3549 have an EU (EUVD) identifier?

Yes. CVE-2026-3549 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13168.

When was CVE-2026-3549 published?

CVE-2026-3549 was published on 2026-03-19 and last updated on 2026-06-17.

CVE-2026-3549

CVE-2026-3549 is a critical-severity vulnerability in Wolfssl with a CVSS 3.x base score of 9.8. 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-122.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 8.3
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13168
Weakness: CWE-122
Affected product: Wolfssl
Published: 2026-03-19
Last modified: 2026-06-17

Description

Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.

Frequently asked questions

What is CVE-2026-3549?: Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.
How severe is CVE-2026-3549?: CVE-2026-3549 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-3549 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-3549?: CVE-2026-3549 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-3549?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-3549 have an EU (EUVD) identifier?: Yes. CVE-2026-3549 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13168.
When was CVE-2026-3549 published?: CVE-2026-3549 was published on 2026-03-19 and last updated on 2026-06-17.

References

https://github.com/wolfSSL/wolfssl/pull/9817

Affected products (1)

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

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