CVE-2026-34873 json
An issue was discovered in Mbed TLS 3.5.0 through 4.0.0.
published 7mo ago modified 4mo ago also EUVD-2026-18064
- cvss
- 9.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 16%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- trustedfirmware mbed_tls 3.6.6, 4.1.0
- mbedtls Debian 13 3.6.6-0.1~deb13u1
- mbedtls Debian 14 3.6.6-0.1
debian advisories DEBIAN-CVE-2026-34873
- mbedtls openSUSE Tumbleweed 3.6.6-1.1
opensuse advisories openSUSE-SU-2026:10498-1
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What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-34873 updated cvss 10.0
mbedtls: Mbed TLS: Client impersonation during TLS 1.3 session resumption
-
Red Hat All currently supported Red Hat productsnot affected: vulnerable code not present
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 7mo ago
Exploit prediction
0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| CNA | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
Classification
- Weakness
-
- CWE-287 Improper Authentication
References
Sources
- CVE List CVE-2026-34873
- NVD CVE-2026-34873
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.