CVE-2020-25659

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.

Published: 2021-01-11 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-25659 is rated Moderate Risk (54.1/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.45%). EPSS rose +1.69% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-25659

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.76% 2.45% +1.69%
2 2026-04-21 0.25% 0.76% +0.51%
3 2025-11-21 — 0.25% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-25659

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-25659

GitHub Security Advisory for CVE-2020-25659

GHSA-hggm-jpg3-v476 · Severity: high · Ecosystem: pip — RSA decryption vulnerable to Bleichenbacher timing vulnerability

OS Trackers for CVE-2020-25659

vendor priority summary link
alpine medium CVE-2020-25659: 1 source package rows (py3-cryptography); 9 state rows across 8 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community, edge-main); fixed 9, open 0. https://security.alpinelinux.org/vuln/CVE-2020-25659
debian not yet assigned CVE-2020-25659 not yet assigned priority: Debian including 1 source packages (python-cryptography), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-25659
redhat medium — https://access.redhat.com/security/cve/CVE-2020-25659
suse medium CVE-2020-25659 severity moderate: SUSE including 289 source package names (0.1.75:python3-cryptography-2.8-7.4.1, 0.45.0.8.14.1:python3-cryptography-2.8-3.3.1, …), 715 product×package rows across 402 product lines (Container bci/kiwi, Container caasp/v4/k8s-sidecar, … (402 product lines)): Fixed 608, Known Affected 103, Known Not Affected 4. https://www.suse.com/security/cve/CVE-2020-25659/
ubuntu medium CVE-2020-25659 medium priority: Ubuntu including 1 source packages (python-cryptography), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): released 5, DNE 1. https://ubuntu.com/security/CVE-2020-25659

Affected software / configurations for CVE-2020-25659

Vendor Product Version Raw CPE
cryptography.io cryptography 3.2 cpe:2.3:a:cryptography.io:cryptography:3.2:*:*:*:*:python:*:*
oracle communications_cloud_native_core_network_function_cloud_native_environment 1.10.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*

References for CVE-2020-25659

cvelogic Threat Intelligence