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Fencer Vulns
critical 9.1

CVE-2020-36242 json

PyCA Cryptography symmetrically encrypting large values can lead to integer overflow

published 2021-02-07 5 y ago modified 2026-06-17 4 mo ago also GHSA-rhm9-p9w5-fwm7 , PYSEC-2021-63 , EUVD-2021-0048

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
6.8%
EPSS 6.8% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi cryptography 3.3.2
  • cryptography.io cryptography 3.3.2
  • python-cryptography Debian 14, Debian 13, Debian 12 3.3.2-1

debian advisories DEBIAN-CVE-2020-36242

  • rh-python38-babel RHEL 3 SOFTWARE_COLLECTIONS 2.7.0-12.el7
  • rh-python38-python RHEL 3 SOFTWARE_COLLECTIONS 3.8.11-2.el7
  • rh-python38-python-pip RHEL 3 SOFTWARE_COLLECTIONS 19.3.1-2.el7
  • rh-python38-python-idle RHEL 3 SOFTWARE_COLLECTIONS 3.8.11-2.el7
  • rh-python38-python-libs RHEL 3 SOFTWARE_COLLECTIONS 3.8.11-2.el7
  • rh-python38-python-lxml RHEL 3 SOFTWARE_COLLECTIONS 4.4.1-7.el7
  • rh-python38-python-test RHEL 3 SOFTWARE_COLLECTIONS 3.8.11-2.el7
  • rh-python38-python-babel RHEL 3 SOFTWARE_COLLECTIONS 2.7.0-12.el7

red hat advisories RHSA-2021:3254RHSA-2021:2239RHSA-2021:1608

  • protobuf SLE Module for Public Cloud 15 SP1, SLE Installer Updates 15 SP1, SLES for SAP 15 SP1 +2 more 3.9.2-150100.8.3.3
  • python-psutil SLE Module for Public Cloud 15 SP1, Enterprise Storage 7, SLES for SAP 15 SP2 +5 more 5.9.1-150100.6.6.3
  • python-requests SLE Module for Public Cloud 15 SP1, Enterprise Storage 7, SLES for SAP 15 SP2 +5 more 2.25.1-150100.6.13.3
  • grpc SLE Module for Public Cloud 15 SP1 1.25.0-150100.3.3.3
  • python-avro SLE Module for Public Cloud 15 SP4, SLE Module for Public Cloud 15 SP3, SLE Module for Public Cloud 15 SP2 +1 more 1.11.0-150100.3.3.3
  • python-knack SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4, SLE Module for Public Cloud 15 SP3 +3 more 0.9.0-150100.3.7.3
  • python-pytest SLE Module for Public Cloud 15 SP2, SLE Module for Public Cloud 15 SP1 3.10.1-150000.7.5.1
  • azure-cli-core SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4, SLE Module for Public Cloud 15 SP3 +3 more 2.17.1-150100.6.18.1

suse advisories SUSE-SU-2023:2783-2SUSE-SU-2023:2783-1SUSE-SU-2023:1838-1SUSE-SU-2023:0604-1SUSE-RU-2022:4567-1SUSE-SU-2021:0696-1

  • python-cryptography openSUSE Tumbleweed 50.0.0-1.1
  • python-cryptography openSUSE Tumbleweed 3.3.2-2.4
  • python-cryptography openSUSE Tumbleweed 42.0.5-1.1
  • python-cryptography openSUSE Leap 15.2 2.8-lp152.2.6.1

opensuse advisories openSUSE-SU-2026:11468-1openSUSE-SU-2024:11223-1openSUSE-SU-2024:13819-1openSUSE-SU-2021:0349-1

  • python-cryptography Rocky Linux 8 3.2.1-4.el8

rocky linux advisories RLSA-2021:1608

  • py3-cryptography Alpine 3.13 3.3.2-r0
  • py3-cryptography Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 3.2.2-r0

alpine advisories ALPINE-CVE-2020-36242

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-cryptography Arch Linux 3.4-1

arch linux advisories AVG-1541

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-36242 updated cvss 8.2

python-cryptography: Large inputs for symmetric encryption can trigger integer overflow leading to buffer overflow

  • Red Hat Ansible Automation Platform 1.2 cryptography, python-cryptography
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Ansible Engine 2 python-cryptography
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Ansible Tower 3 cryptography
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 7 python-cryptography, python2-cryptography
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 python-cryptography, python3-cryptography Red Hat OpenStack Platform 13 (Queens) python-cryptography, python2-cryptography
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Quay 3 quay/quay-rhel8
    affected: workaround, no fix available
  • Red Hat Enterprise Linux BaseOS (v. 8) python-cryptography 3.2.1-4.el8, python3-cryptography 3.2.1-4.el8
    fixed: vendor fix RHSA-2021:1608
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python38-babel 2.7.0-12.el7, rh-python38-python 3.8.11-2.el7, rh-python38-python-lxml 4.4.1-7.el7, rh-python38-python-pip 19.3.1-2.el7, rh-python38-python-idle 3.8.11-2.el7, rh-python38-python-libs 3.8.11-2.el7, +9 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python38-babel 2.7.0-12.el7, rh-python38-python 3.8.11-2.el7, rh-python38-python-lxml 4.4.1-7.el7, rh-python38-python-pip 19.3.1-2.el7, rh-python38-python-idle 3.8.11-2.el7, rh-python38-python-libs 3.8.11-2.el7, +9 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python38-babel 2.7.0-12.el7, rh-python38-python 3.8.11-2.el7, rh-python38-python-lxml 4.4.1-7.el7, rh-python38-python-pip 19.3.1-2.el7, rh-python38-python-idle 3.8.11-2.el7, rh-python38-python-libs 3.8.11-2.el7, +9 more
    fixed: vendor fix RHSA-2021:3254
show 2 more
  • Red Hat Virtualization 4 Hypervisor for RHEL 8 redhat-virtualization-host 4.4.6-20210527.3.el8_4, redhat-virtualization-host-image-update 4.4.6-20210527.3.el8_4
    fixed: vendor fix RHSA-2021:2239
  • Red Hat CloudForms Management Engine 5 python2-cryptography Red Hat Enterprise Linux 9 python-cryptography, python3-cryptography Red Hat Virtualization 4 Hypervisor for RHEL 8 elfutils-debuginfod-client 0.182-3.el8 Red Hat Virtualization 4 Management Agent for RHEL 7 Hosts cockpit-ovirt 0.15.0-2.el8ev, ovirt-hosted-engine-ha 2.4.7-1.el8ev, cockpit-ovirt-dashboard 0.15.0-2.el8ev Red Hat RHEL 8-based RHEV-H for RHEV 4 (build requirements) imgbased 1.2.19-1.el8ev, python3-imgbased 1.2.19-1.el8ev, scap-security-guide 0.1.54-1.el8ev, scap-security-guide-rhv 0.1.54-1.el8ev, redhat-release-virtualization-host 4.4.6-1.el8ev, redhat-virtualization-host-image-update-placeholder 4.4.6-1.el8ev
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

6.80% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/pyca/cryptography/issues/5615 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:N/A:P
GitHub 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi cryptography
>=3.1, <3.3.2
3.3.2

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.