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Vulnerabilities

Vulnerability · CVE-2026-3549

Heap Overflow in TLS 1.3 ECH parsing.

Published Mar 19, 2026 · catalog updated Jun 17, 2026 · Heap Overflow in TLS

Check if you run it

No confirmed exploitation is on record for CVE-2026-3549. EPSS is 0.57%. Act only if a listed version of Heap Overflow in TLS is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Heap Overflow in TLS).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.57%
Remediation
Not established
Affected products
cpe wolfssl/wolfssl

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe wolfssl/wolfsslversion unspecified

How to fix CVE-2026-3549

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3549. EPSS is 0.57%. Act only if a listed version of Heap Overflow in TLS is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-122: Heap-based Buffer Overflow. EPSS 0.57%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 19, 2026 · NIST NVD

    Detected

    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.

  2. Jun 17, 2026 · NIST NVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-3549

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3549

    30-day exploitation probability 0.6%

    first.org
  • NIST NVDVulnerability recordCVE-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 evolv

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.