CVE-2026-28684CWE-59CWE-61

python-dotenv: Symlink following in set_key allows arbitrary file overwrite via cross-device rename fallback

Medium · published April 20, 2026

CVSS v3.1
6.6
EPSS
0%
Percentile
7.8
In the wild
Unconfirmed
What it is

python-dotenv reads key-value pairs from a .env file and can set them as environment variables. Prior to version 1.2.2, `set_key()` and `unset_key()` in python-dotenv follow symbolic links when rewriting `.env` files, allowing a local attacker to overwrite arbitrary files via a crafted symlink when a cross-device rename fallback is triggered. Users should upgrade to v.1.2.2 or, as a workaround, apply the patch manually.

The record
Technical detail
CVSS v3.1
6.6 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00187 · 7.8th percentile
Weaknesses
CWE-59 · Improper Link Resolution Before File Access ('Link Following'); CWE-61 · UNIX Symbolic Link (Symlink) Following
Published
2026-04-20T16:25Z
EPSS history
Timeline
  • 20 APR 16:25Z
    python-dotenv: Symlink following in set_key allows arbitrary file overwrite via cross-device rename fallback
    cvelistv5