What is CVE-2018-16149?

CVE-2018-16149 is a medium-severity vulnerability in Axtls Project, classified under Improper Verification of Cryptographic Signature. CVSS score: 5.9/10. Published 2018-11-07.

How severe is CVE-2018-16149?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Axtls Project

CVE-2018-16149

In sig_verify() in x509.c in axTLS version 2.1.3 and before, the PKCS#1 v1.5 signature verification blindly trusts the declared lengths in the ASN.1 structure. Consequently, when small public exponents are being used, a remote attacker can generate purposefully crafted signatures (and put them on X.509 certificates) to induce illegal memory access and crash the verifier.

Published 2018-11-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.007 (51.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Axtls Project

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c (Patch, Third Party Advisory)
sourceforge.net/p/axtls/mailman/message/36459928/ (mailing-list, Exploit, Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2018-16149?: CVE-2018-16149 is a medium-severity vulnerability in Axtls Project, classified under Improper Verification of Cryptographic Signature. CVSS score: 5.9/10. Published 2018-11-07.
How severe is CVE-2018-16149?: Medium severity. CVSS v3 base score is 5.9 out of 10.