#VU50367 Covert Timing Channel in python-cryptography - CVE-2020-25659

Vulnerability identifier: #VU50367

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-25659

CWE-ID: CWE-385

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
python-cryptography
Universal components / Libraries / Programming Languages & Components

Vendor: Python Cryptographic Authority

Description

The vulnerability allows a remote non-authenticated attacker to gain access to sensitive information.

python-cryptography 3.2 is vulnerable to Bleichenbacher timing attacks in the RSA decryption API, via timed processing of valid PKCS#1 v1.5 ciphertext.

Mitigation
Install update from vendor's website.

Vulnerable software versions

python-cryptography: 3.2

---

External links
https://github.com/pyca/cryptography/pull/5507/commits/ce1bef6f1ee06ac497ca0c837fbd1c7ef6c2472b

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.