CVE-2020-25658: It was found that python-rsa is vulnerable to Bleichenbacher timing attacks

This week

HIGH 7.5REMOTEWATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2020-25658 is a high-severity flaw (CVSS 7.5) affecting python-rsa, openstack platform, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

It was found that python-rsa is vulnerable to Bleichenbacher timing attacks. An attacker can use this flaw via the RSA decryption API to decrypt parts of the cipher text encrypted with RSA.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 24%)
CISA exploited list	No
Weakness	CWE-385, CWE-327
Published	2020-11-12
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: fedoraproject · python-rsa project · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-11-12 14:15 UTCPublished CVE record published
2026-06-17 03:07 UTCUpdated Record last modified

python-rsa project python-rsa UPGRADE

Affected: >= 2.1 and < 4.7

Fixed in: 4.7

Safe to downgrade to: a release before 2.1

1. Check installed version

apt-cache policy python-rsa || rpm -q python-rsa || python-rsa --version

2. UPGRADE to 4.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade python-rsa

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade python-rsa

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.1 (Debian / Ubuntu)

apt-cache madison python-rsa sudo apt install python-rsa=<VERSION_BEFORE_2.1> sudo apt-mark hold python-rsa

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list python-rsa sudo dnf downgrade python-rsa-<VERSION_BEFORE_2.1> sudo dnf versionlock add python-rsa

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat openstack platform DOWNGRADE

Affected: 13.0 · 16.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 13.0

1. Check installed version

apt-cache policy openstack-platform || rpm -q openstack-platform || openstack-platform --version

2. No fixed release: DOWNGRADE to a release before 13.0 (Debian / Ubuntu)

apt-cache madison openstack-platform sudo apt install openstack-platform=<VERSION_BEFORE_13.0> sudo apt-mark hold openstack-platform

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openstack-platform sudo dnf downgrade openstack-platform-<VERSION_BEFORE_13.0> sudo dnf versionlock add openstack-platform

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

fedoraproject fedora MITIGATE

Affected: 33 · 34 · 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 33

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-25658?

python-rsa: upgrade to 4.7; openstack platform: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-25658 being exploited?

CVE-2020-25658 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-25658 affect?

CVE-2020-25658 affects python-rsa, openstack platform, fedora. Severity is high (CVSS 7.5). It was found that python-rsa is vulnerable to Bleichenbacher timing attacks. An attacker can use this flaw via the RSA decryption API to decrypt parts of the cipher text encrypted with RSA.

How urgent is CVE-2020-25658?

Priority 60/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Python vulnerabilities · OpenStack vulnerabilities

Related CVEs

CVE-2020-13757 HIGH 7.5 UPGRADE MITIGATE Python-RSA before 4.1 ignores leading '\0' bytes during decryption of ciphertext

References

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