CVE-2026-73064
LowCVSS 2.9Exploitation Probability (EPSS)
Low risk1th percentile - higher than 1% of all known CVEs
Summary
In Mbed TLS 3.2.0 through 3.6.6 and 4.0.0 through 4.1.0, an attacker who can cause an entropy source to fail can remove or inject bytes into the start of the TLS stream. This only affects TLS 1.3 servers.
Risk Assessment
An attacker can manipulate the beginning of the TLS stream, potentially compromising communication integrity and allowing data injection. This affects TLS 1.3 servers using the vulnerable Mbed TLS version.
Recommendation
Update Mbed TLS to a version containing the fix (later than 3.6.6 or 4.1.0) and ensure reliable entropy sources in the server environment.
Other vulnerabilities in Mbed TLS
See all- CVE-2026-34877Critical
A vulnerability in Mbed TLS (versions 2.19.0 to 3.6.5 and 4.0.0) is caused by insufficient protection of serialized SSL structures. An attacker can modify these structures, leading to memory corruption and potential arbitrary code execution.
- CVE-2026-25832Low
In Mbed TLS 3.6.x before 3.6.7 and 4.1.x before 4.1.2, the TLS 1.3 client accepts a HelloRetryRequest selecting a group that was not advertised. This can violate TLS 1.3 protocol negotiation expectations.
- CVE-2026-34876High
Mbed TLS 3.x before 3.6.6 has an out-of-bounds read vulnerability in mbedtls_ccm_finish() due to missing validation of the tag_len parameter. An attacker can obtain adjacent CCM context data.
Original NVD description (English source)
In Mbed TLS 3.2.0 though 3.6.6 and 4.0.0 through 4.1.0, an attacker who can cause an entropy source to fail can remove or inject bytes into the start of the TLS stream. This only affects TLS 1.3 servers.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS