OpenVPN 2.6.0-2.6.19/2.7_alpha1-2.7.1 UAF via TLS session promotion
CVE-2026-40215 Published on June 8, 2026
A race condition in OpenVPN 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 allows remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion.
Weakness Types
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2026-40215 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2026-40215
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Affected Versions
OpenVPN:- Version 2.6.0, <= 2.6.19 is affected.
- Version 2.7_alpha1, <= 2.7.1 is affected.