CVE-2021-42771: Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized

Q: How do I fix CVE-2021-42771?

babel: upgrade to 2.9.1; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-42771 being exploited?

CVE-2021-42771 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-42771 affect?

CVE-2021-42771 affects babel, debian linux. Severity is high (CVSS 7.8). Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory traversal, leading to code execution.

Q: How urgent is CVE-2021-42771?

Priority 51/100. High severity; Public exploit reference; On your watchlist

This month

HIGH 7.8WATCHLISTUPGRADEMITIGATE

CVE-2021-42771 is a high-severity flaw (CVSS 7.8) affecting babel, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory traversal, leading to code execution.

Why this priority

High severity
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.8% (top 44%)
CISA exploited list	No
Weakness	CWE-22
Published	2021-10-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · pocoo

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

Am I affected?

Timeline

2021-10-20 21:15 UTCPublished CVE record published
2026-06-17 04:10 UTCUpdated Record last modified

pocoo babel UPGRADE

Affected: < 2.9.1

Fixed in: 2.9.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy babel || rpm -q babel || babel --version

2. UPGRADE to 2.9.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade babel

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade babel

Note

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

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

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-2021-42771?

babel: upgrade to 2.9.1; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42771 being exploited?

CVE-2021-42771 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-2021-42771 affect?

CVE-2021-42771 affects babel, debian linux. Severity is high (CVSS 7.8). Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory traversal, leading to code execution.

How urgent is CVE-2021-42771?

Priority 51/100. High severity; Public exploit reference; On your watchlist

Software pages

Python vulnerabilities · Debian vulnerabilities

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References

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