Vulnerability · CVE-2026-34877
An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0.
Published Apr 2, 2026 · catalog updated Jul 24, 2026 · mbed tls
Check if you run it
No confirmed exploitation is on record for CVE-2026-34877. EPSS is 0.73%. Act only if a listed version of mbed tls is installed.
Gaps on this record
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Critical9.8
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.73%
- Remediation
- Advisory link
- Affected products
- cpe arm/mbed tls · cpe trustedfirmware/mbed tls
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 corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- cpe arm/mbed tlsversion unspecified
- cpe trustedfirmware/mbed tls4.0.0
How to fix CVE-2026-34877
Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-34877. EPSS is 0.73%. Act only if a listed version of mbed tls is installed.
Which versions are affected?
Compare what you have installed with trustedfirmware/mbed tls 4.0.0. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-250: Execution with Unnecessary Privileges; CWE-502: Deserialization of Untrusted Data. EPSS 0.73%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Apr 2, 2026 · NIST NVD
Detected
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 corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.
Jul 24, 2026 · NIST NVD
Updated
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 corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.
Sources
- CVE.orgVulnerability recordCVE-2026-34877
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-34877
30-day exploitation probability 0.7%
first.org - NIST NVDVulnerability recordCVE-2026-34877
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 corruption, leading to arbitrary code executi
nvd.nist.gov
References
Freshness
Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.