What is CVE-2019-6439?

CVE-2019-6439 is a critical-severity vulnerability in Wolfssl, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2019-01-16.

How severe is CVE-2019-6439?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2019-6439 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Wolfssl

CVE-2019-6439

examples/benchmark/tls_bench.c in a benchmark tool in wolfSSL through 3.15.7 has a heap-based buffer overflow.

Vulnerability class: Buffer Overflow

Published 2019-01-16 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.026 (84.4th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 84th percentile — 84.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.026 · newest: 0.026 · change: 0.000

Affected products

Wolfssl

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

Public proof-of-concept exploits

References

www.securityfocus.com/bid/106640 (VDB Entry, Third Party Advisory, vdb-entry)
github.com/wolfSSL/wolfssl/issues/2032 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2019-6439?: CVE-2019-6439 is a critical-severity vulnerability in Wolfssl, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2019-01-16.
How severe is CVE-2019-6439?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2019-6439 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.