Is CVE-2021-33026 actively exploited?

No active exploitation of CVE-2021-33026 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-33026 be exploited remotely?

Yes. CVE-2021-33026 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-33026?

CVE-2021-33026 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-33026

CRITICAL

CVE-2021-33026

CWE-502Published: May 13, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

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

NVD Source

Technical Analysis

CVE-2021-33026 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-502): Insecure deserialization vulnerabilities allow attackers to inject malicious objects during deserialization, potentially enabling remote code execution.