CVE-2019-18840
CVSS v3
7.5
HIGH
EPSS Score
2.0 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
In wolfSSL 4.1.0 through 4.2.0c, there are missing sanity checks of memory accesses in parsing ASN.1 certificate data while handshaking. Specifically, there is a one-byte heap-based buffer overflow inside the DecodedCert structure in GetName in wolfcrypt/src/asn.c because the domain name location index is mishandled. Because a pointer is overwritten, there is an invalid free.
Technical details
- Published
- 2019-11-09
Frequently asked questions
What is CVE-2019-18840?
In wolfSSL 4.1.0 through 4.2.0c, there are missing sanity checks of memory accesses in parsing ASN.1 certificate data while handshaking. Specifically, there is a one-byte heap-based buffer overflow inside the DecodedCert structure in GetName in wolfcrypt/src/asn.c because the domain name location index is mishandled. Because a pointer is overwritten, there is an invalid free.
Is CVE-2019-18840 actively exploited?
Active exploitation of CVE-2019-18840 has not been confirmed. Its EPSS score was 2.0% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2019-18840?
CVE-2019-18840 has a CVSS v3 base score of 7.5 (HIGH severity).
Is CVE-2019-18840 affecting your environment?
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