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CVE-2026-27459

pyOpenSSL DTLS cookie callback buffer overflow PUBLISHED

Description (CNA)

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.

Affected (CNA)

Vendor / productVersions
pyca / pyopensslaffected >= 22.0.0, < 26.0.0

CWE

CWE-120

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in pyOpenSSL. The set_cookie_generate_callback callback function can be used to generate DTLS cookies. When the callback returns a cookie string or byte sequence longer than 256 bytes, a buffer overflow can be triggered due to a missing bounds checking before copying the data to a fixed-size buffer provided by the underlying OpenSSL library.