CVE-2026-34876
April 3, 2026, 4:10 p.m.
7.5
High
Description
An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Mbed |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-125
Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | mbed | tls | 3.0 | / | / | / | / | / | / | / |
| a | mbed | tls | 3.1 | / | / | / | / | / | / | / |
| a | mbed | tls | 3.2 | / | / | / | / | / | / | / |
| a | mbed | tls | 3.3 | / | / | / | / | / | / | / |
| a | mbed | tls | 3.4 | / | / | / | / | / | / | / |
| a | mbed | tls | 3.5 | / | / | / | / | / | / | / |
| a | mbed | tls | <3.6.6 | / | / | / | / | / | / | / |
| a | mbed | tls | 4.0 | / | / | / | / | / | / | / |
| a | mbed | tls | 4.1 | / | / | / | / | / | / | / |
| a | mbed | tls | <4.6.6 | / | / | / | / | / | / | / |
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: NONE
- Scope: UNCHANGED
- Confidentiality Impact: HIGH
- Integrity Impact: NONE
- Availability Impact: NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Timeline
Published: April 2, 2026, 4:16 p.m.
Last Modified: April 3, 2026, 4:10 p.m.
Last Modified: April 3, 2026, 4:10 p.m.
Status : Awaiting Analysis
CVE has been recently published to the CVE List and has been received by the NVD.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.