CVE-2026-34873: Mbed TLS · A Critical
Source CVE Database V5
Not known to be exploited · CVSS 9.1 Critical.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
Until an official fix is released, organizations should monitor vendor communications closely. Consider disabling TLS 1.3 session resumption if feasible as a temporary mitigation, but verify compatibility and impact before applying such measures.
Description
A critical vulnerability in Mbed TLS versions 3.5.0 through 4.0.0 allows remote attackers to impersonate clients during the resumption of a TLS 1.3 session. This flaw, classified as improper authentication (CWE-287), can be exploited without authentication or user interaction, impacting confidentiality and integrity. No official patch or remediation details are currently available. There are no known exploits in the wild at this time.