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Vulnerability · Published May 13, 2021 · Assigned by mitre

CVE-2021-33026

Critical 9.8

In plain English

A critical-severity unsafe deserialization in the flask-caching package (Debian). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 7.3% (higher than 94% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)7.3%top 5.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

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

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12flask-cachingno fix listedDEBIAN-CVE-2021-33026
Debian:13flask-cachingno fix listedDEBIAN-CVE-2021-33026
Debian:14flask-cachingno fix listedDEBIAN-CVE-2021-33026
PyPIflask-cachingno fix listedGHSA-656c-6cxf-hvcv

Affected products (as reported)

VendorProductVersions
n/a n/a n/a

Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References