A vulnerability in the python cryptographic library as used in Juniper Networks Junos OS and Junos OS Evolved allows an attacker to perform timing oracle attacks against RSA decryption. As the open source community notes for this component change to address this attack, this update to the cryptographic library attempts to make RSA PKCS #1 v1.5 decryption more constant-time ( O(1) time, to be more independent between total operations performed related to input sizes), to protect against Bleichenbacher vulnerabilities.
Due to limitations imposed by the python-cryptography API, it cannot completely mitigate this vulnerability and a future release of the python-cryptography project will contain a new API which is designed to be resilient to these attacks for contexts where it is required, so as not to leak secret information through timing analysis.
This issue affects:
Juniper Networks Junos OS
This issue affects Juniper Networks Junos OS Evolved versions prior to 20.4R3-S1.
This issue affects all versions of Wind River Linux on all products.
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was seen during production usage.
This issue is also known as Bleichenbacher Attack.
This issue has been assigned CVE-2020-25659 .
The following software releases have been updated to resolve this specific issue:
Junos OS: 19.4R2-S4, 19.4R3-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2, 20.4R1-S1, 20.4R2, 21.1R1, and all subsequent releases.
Junos OS Evolved: 20.4R3-S1, and all subsequent releases in 20.4R3-Sy release branch.
This issue is being tracked as 1553116 and 1602272 .
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
2021-10-13: Initial Publication. 2021-10-25: Affects All Junos products, not only SRX Series. Advisory updated accordingly.