CVE-2021-33026 – flask-caching

Package

Manager: pip
Name: flask-caching
Vulnerable Version: >=0 <=1.10.1

Severity

Level: Medium

CVSS v3.1: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N

CVSS v4.0: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS: 0.1911 pctl0.95113

Details

Deserialization of Untrusted Data in Flask-Caching Flask-Cache adds easy cache support to Flask. The Flask-Caching extension through 1.10.1 for Flask relies on Pickle for serialization, which may lead to remote code execution or local privilege escalation. If an attacker gains access to cache storage (e.g., filesystem, Memcached, Redis, etc.), they can construct a crafted payload, poison the cache, and execute Python code. However, this is not a high-severity issue, as for an attack like this to work, an attacker must: 1. Be able to write arbitrary values to the cache 2. Be able to generate a cache key that will collide with a value being read by the application 3. Cause the application to read a maliciously-injected value Any situation where all 3 of those is true is a situation where the application has larger problems; for example, if someone's able to inject malicious cached rendered pages into a Flask app's cache, then they can make the website say literally anything they want, regardless of whether it involves the execution of remote code. Basically, the Pickle vulnerability follows from a website already being extremely vulnerable (due to conditions 1 and 2 being met).

Metadata

Created: 2021-06-18T18:33:40Z
Modified: 2022-09-20T13:31:06Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/06/GHSA-656c-6cxf-hvcv/GHSA-656c-6cxf-hvcv.json
CWE IDs: ["CWE-269", "CWE-502"]
Alternative ID: GHSA-656c-6cxf-hvcv
Finding: F096
Auto approve: 1