Vulnerability

CVE-2026-34877

Critical· 9.8CVSS9.8EPSS0%

.rules3/5

An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corru

Threat signal

98/100

Severe

Severity

critical

CVSS

9.8

EPSS

Active

CVSS

v3.1via NVDOpen in FIRST calculator →

9.8/ 10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

0.23%

probability of exploitation in next 30 days

p46

higher than 46% of all CVEs

3-day trend↑ 0pp

Low exploitation likelihood — defer if no other signals fire.

Vendor VEX

No VEX statements published for CVE-2026-34877. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCTrack

Total impact on non-trivial mission systems

exploitation: none
automatable: yes
impact: total
mission: support

Lifecycle

2026-04-02Published
2026-06-05Last modified1 source

References

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.