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CVE-2018-16253

20
FAUCET Score

CVE-2018-16253 is a critical vulnerability in axTLS version 2.1.3 and earlier, specifically within the sig_verify() function in x509.c. This flaw allows remote attackers to forge PKCS#1 v1.5 signatures by exploiting improper ASN.1 metadata verification, particularly when small public exponents are in use. The vulnerability has a CVSS v3.0 score of 5.9 (Medium), indicating a network-based attack with high impact on integrity, but requiring high attack complexity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.1.3CPE matchmatch criteria
cpe:2.3:a:axtls_project:axtls:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.9MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
0.62%
Probability of exploitation in next 30 days
EPSS Percentile
46.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0062 is in the 8th percentile among its peer group of 19,955 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c
PatchThird Party Advisory
sourceforge.net / p/axtls/mailman/message/36459928
ExploitThird Party Advisory