CVE-2021-33026

highpriority · attend · 52EPSS 0.073 · 94 %ileexploit · PoCDEEURUUS
grimoire priorityP1 · Urgent
Exploitable?
Public exploit
2 exploits · PoC
Likely / severe?
7.35% (94th) EPSS
CVSS 7.5 · high
Is it mine?
12 products
Check your exposure
Who says so?
6 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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

01

cvss

Technical severity, 0–10. One row per scoring source.

9.8
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 4.2–9.8

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9
v3.19.8criticalAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 3.9 · impact 5.9
v3.14.2mediumCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:Nsecondary · OSV
v3.19.3criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Psecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

04

exploits (2)

Public proof-of-concept and weaponised exploit code.

05

affected products (12)

Products and version ranges known to be affected.

06

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2023-0426IBM Spectrum Protect: Mehrere SchwachstellenDeutsch2022-03-13csaf · cert_bundDE

    Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in IBM Spectrum Protect ausnutzen, um einen 'Denial of Service'-Zustand herbeizuführen, Sicherheitsmaßnahmen zu umgehen, einen 'Cross-Site-Scripting'-Angriff durchzuführen, beliebigen Code auszuführen, sensible Informationen offenzulegen und seine Privilegien zu erweitern.

  • GHSA-656c-6cxf-hvcvDeserialization of Untrusted Data in Flask-Caching2021-06-18ghsa · osvUS

    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).

07

also known as (5)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

10

references (7)

External citations — patches, advisories, analysis.

scry

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