Deserialization in Flask-Caching Project
CVE-2021-33026
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. NOTE: a third party indicates that exploitation is extremely unlikely unless the machine is already compromised; in other cases, the attacker would be unable to write their payload to the cache and generate the required collision
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.071 (94.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 94.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.070 · newest: 0.071 · change: +0.001
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/sh4nks/flask-caching/pull/209 (Patch, Third Party Advisory)
- github.com/pallets-eco/flask-caching/pull/209 (Patch, Third Party Advisory, Issue Tracking)
Frequently asked questions
- What is CVE-2021-33026?
- CVE-2021-33026 is a critical-severity vulnerability in Flask-Caching Project, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2021-05-13.
- How severe is CVE-2021-33026?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2021-33026 known to be exploited?
- 9 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.