Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-34873

26
FAUCET Score

CVE-2026-34873 is a critical vulnerability affecting Mbed TLS versions 3.5.0 through 4.0.0, allowing client impersonation during TLS 1.3 session resumption. Rated 9.1 CRITICAL, this vulnerability is network-exploitable with low attack complexity and requires no user interaction, potentially leading to high confidentiality and integrity impacts. There is currently no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed on the CISA KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.5.0, < 3.6.6CPE matchmatch criteria
cpe:2.3:a:trustedfirmware:mbed_tls:*:*:*:*:*:*:*:*
>= 4.0.0, < 4.1.0CPE matchmatch criteria
cpe:2.3:a:trustedfirmware:mbed_tls:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.24%
Probability of exploitation in next 30 days
EPSS Percentile
15.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0024 is in the 1st percentile among its peer group of 36,897 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

microsoft2026-Apr/CVE-2026-34873Moderate

An issue was discovered in Mbed TLS 3.5.0 through 4.0.0. Client impersonation can occur while resuming a TLS 1.3 session.

Apr 14, 2026

References

mbed-tls.readthedocs.io / en/latest/security-advisories
Vendor Advisory
mbed-tls.readthedocs.io / en/latest/security-advisories/mbedtls-security-advisory-2026-03-client-impersonation-while-resuming-tls13-session
Vendor Advisory