CVE-2020-36242

Exp

In the cryptography package before 3.3.2 for Python, certain sequences of update calls to symmetrically encrypt multi-GB values could result in an integer overflow and buffer overflow, as demonstrated by the Fernet class.

Published: 2021-02-07 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-36242 is rated High Exploit Risk (89/100): CVSS Critical severity, with high exploitation likelihood (EPSS 6.72%, 93th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +5.14% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2020-36242

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-36242

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 1.57% 6.72% +5.14%
2 2026-04-03 1.27% 1.57% +0.30%
3 2026-03-04 — 1.27% —

Full EPSS history (48 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-36242

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H 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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 [email protected]
6.4 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 4.9 [email protected]

Weakness enumeration for CVE-2020-36242

GitHub Security Advisory for CVE-2020-36242

GHSA-rhm9-p9w5-fwm7 · Severity: high · Ecosystem: pip — PyCA Cryptography symmetrically encrypting large values can lead to integer overflow

OS Trackers for CVE-2020-36242

vendor priority summary link
alpine critical CVE-2020-36242: 1 source package rows (py3-cryptography); 13 state rows across 10 repos (3.11-main, 3.12-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community, edge-main); fixed 8, open 5. https://security.alpinelinux.org/vuln/CVE-2020-36242
debian not yet assigned CVE-2020-36242 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-2020-36242
gentoo normal CVE-2020-36242: 1 GLSA(s) (202407-06), 1 atom(s) (dev-python/cryptography); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-36242
redhat medium — https://access.redhat.com/security/cve/CVE-2020-36242
suse high CVE-2020-36242 severity important: SUSE including 275 source package names (0.45.0.8.14.1:python3-cryptography-2.8-3.6.1, 0.49.0.14.2.89:python3-cryptography-2.8-3.6.1, …), 458 product×package rows across 147 product lines (Container ses/7.1/cephcsi/cephcsi, Container ses/7.1/rook/ceph, … (147 product lines)): Fixed 359, Known Affected 92, Known Not Affected 7. https://www.suse.com/security/cve/CVE-2020-36242/
ubuntu medium CVE-2020-36242 medium priority: Ubuntu including 1 source packages (python-cryptography), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): not-affected 4, DNE 1, released 1. https://ubuntu.com/security/CVE-2020-36242

Affected software / configurations for CVE-2020-36242

Vendor Product Version Raw CPE
cryptography.io cryptography < 3.3.2 cpe:2.3:a:cryptography.io:cryptography:*:*:*:*:*:python:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
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-2020-36242

cvelogic Threat Intelligence