The Flask-Caching extension through 1.10.1 for Flask relies on Pickle for serialization…
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution, Privilege escalation
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and GitHub. Impact type from CWE-502 and CWE-269.
Summary
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
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | Flask-Caching (PyPI) | up to 1.10.1 | — | No fix listed | GHSA-656c-6cxf-hvcv |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- Flask-Caching (PyPI) Vendor— Affected up to 1.10.1 Fixed in — No fix listed GHSA-656c-6cxf-hvcv
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:flask-caching_project:flask-caching:*:*:*:*:*:flask:*:* | up to 1.10.1 | Vulnerable | Flask-caching Project |
- cpe:2.3:a:flask-caching_project:flask-caching:*:*:*:*:*:flask:*:* Versions up to 1.10.1 Vulnerable ·Flask-caching Project
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-33026
- 2026-10-03 Alias added: GHSA-656c-6cxf-hvcv
References
Patch 2
Advisory 2
Sources
- CVE-2021-33026 · CVE Program
- CVE-2021-33026 · NVD
- FIRST EPSS
- GHSA-656c-6cxf-hvcv · GitHub Advisory Database · CC BY 4.0
- CVE-2021-33026 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences