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CVE-2026-3549

Wolfssl buffer overflow

9.8 CRITICALEPSS 0.55%
  1. Published19 Mar 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Wolfssl< 5.9.0

Remediation

Fixed in
Wolfssl≥ 5.9.0

References

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Frequently asked

Is CVE-2026-3549 being actively exploited?

CVE-2026-3549 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.55%.

How severe is CVE-2026-3549?

CVE-2026-3549 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.55% probability of exploitation.

Which products are affected by CVE-2026-3549?

Affected products include Wolfssl.

How do I fix CVE-2026-3549?

Upgrade affected software to a fixed version, for example Wolfssl 5.9.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-3549 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.