CVE-2026-34877 is a critical vulnerability affecting Mbed TLS versions 2.19.0 through 3.6.5, and 4.0.0, stemming from insufficient protection of serialized SSL context or session structures. This flaw allows an attacker to modify these structures, leading to memory corruption and arbitrary code execution due to incorrect use of privileged APIs. Rated 9.8 Critical (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), it presents a severe risk with a network attack vector and low attack complexity, potentially compromising confidentiality, integrity, and availability. While currently not listed in CISA's KEV catalog and lacking public exploit code, it is on the "Hot List" and has garnered some community discussion, indicating its high priority despite a low EPSS score.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
>= 2.19.0, < 3.6.6CPE matchmatch criteria | cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:* | ||
4.0.0CPE matchmatch criteria | cpe:2.3:a:trustedfirmware:mbed_tls:4.0.0:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.
Remediation records are not available for this CVE.