CVE-2021-42771

Exp

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.

Published: 2021-10-20 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-42771 is rated High Exploit Risk (61.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.21%). 1 public exploit reference(s) are indexed (Exploit-DB). 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-2021-42771

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

Exploit prediction scoring system (EPSS) score for CVE-2021-42771

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 2026-03-05 0.13% 0.21% +0.08%
2 2025-11-21 0.23% 0.13% -0.10%
3 2025-11-18 — 0.23% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-42771

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]
7.2 2.0 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.9 10.0 [email protected]

Weakness enumeration for CVE-2021-42771

GitHub Security Advisory for CVE-2021-42771

OS Trackers for CVE-2021-42771

vendor priority summary link
alpine high CVE-2021-42771: 1 source package rows (py3-babel); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2021-42771
debian not yet assigned CVE-2021-42771 not yet assigned priority: Debian including 1 source packages (python-babel), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-42771
redhat medium — https://access.redhat.com/security/cve/CVE-2021-42771
suse high CVE-2021-42771 severity important: SUSE including 323 source package names (0.7.1-rev1.0.0-build2.2.1:python3-Babel-2.8.0-3.3.1, 1.7.7.0.1.1903:python3-Babel-2.8.0-3.3.1, …), 608 product×package rows across 282 product lines (Container ses/7.1/cephcsi/cephcsi, Container ses/7.1/rook/ceph, … (282 product lines)): Fixed 419, Known Affected 189. https://www.suse.com/security/cve/CVE-2021-42771/
ubuntu medium CVE-2021-42771 medium priority: Ubuntu including 1 source packages (python-babel), 8 status rows across 8 suites (bionic, focal, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 7, released 1. https://ubuntu.com/security/CVE-2021-42771

Affected software / configurations for CVE-2021-42771

Vendor Product Version Raw CPE
pocoo babel < 2.9.1 cpe:2.3:a:pocoo:babel:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-42771

cvelogic Threat Intelligence