# flask (PyPI) vulnerabilities

Source: https://junglewise.ai/threats/technologies/flask  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Updated: 13 November 2026, 03:07 UTC. Rebuilt every hour.  
Data: https://junglewise.ai/threats/technologies/flask.json  
License: CC BY 4.0 with a link back

Junglewise Threat Intelligence has tracked 5 vulnerabilities in flask (PyPI): 0 in the last 7 days and 0 in the last 90 days, 0 of them critical and 0 exploited in the wild. The most recent, CVE-2025-47278, was published on 7 July 2026.

## Counts

- Last 7 days: 0
- Last 30 days: 0
- Last 90 days: 0
- All time: 5 (0 critical, 0 exploited in the wild)

## About flask (PyPI)

Python web framework for building web applications.

## Latest flask (PyPI) vulnerabilities

- [CVE-2025-47278: PYSEC-2026-1377 - Flask uses fallback key instead of current signing key](https://junglewise.ai/threats/cve-2025-47278-flask-uses-fallback-key-instead-of-current-signing-key) (medium, CVSS 4, published 7 Jul 2026)
- [CVE-2026-27205: Flask session does not add `Vary: Cookie` header when accessed in some ways](https://junglewise.ai/threats/cve-2026-27205-flask-session-does-not-add-vary-cookie-header-when-accessed-in) (medium, CVSS 4, published 21 Feb 2026)
- [CVE-2023-30861: Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header](https://junglewise.ai/threats/cve-2023-30861-flask-vulnerable-to-possible-disclosure-of-permanent-session) (low, CVSS 3.1, published 2 May 2023)
- [CVE-2019-1010083: Pallets Project Flask is vulnerable to Denial of Service via Unexpected memory usage](https://junglewise.ai/threats/cve-2019-1010083-pallets-project-flask-is-vulnerable-to-denial-of-service-via) (low, CVSS 3.1, published 17 Jul 2019)
- [CVE-2018-1000656: Flask is vulnerable to Denial of Service via incorrect encoding of JSON data](https://junglewise.ai/threats/cve-2018-1000656-flask-is-vulnerable-to-denial-of-service-via-incorrect-encoding) (low, CVSS 3.1, published 20 Aug 2018)

## Most severe flask (PyPI) vulnerabilities

- [CVE-2026-27205: Flask session does not add `Vary: Cookie` header when accessed in some ways](https://junglewise.ai/threats/cve-2026-27205-flask-session-does-not-add-vary-cookie-header-when-accessed-in) (medium, CVSS 4, published 21 Feb 2026)
- [CVE-2025-47278: PYSEC-2026-1377 - Flask uses fallback key instead of current signing key](https://junglewise.ai/threats/cve-2025-47278-flask-uses-fallback-key-instead-of-current-signing-key) (medium, CVSS 4, published 7 Jul 2026)
- [CVE-2018-1000656: Flask is vulnerable to Denial of Service via incorrect encoding of JSON data](https://junglewise.ai/threats/cve-2018-1000656-flask-is-vulnerable-to-denial-of-service-via-incorrect-encoding) (low, CVSS 3.1, published 20 Aug 2018)
- [CVE-2019-1010083: Pallets Project Flask is vulnerable to Denial of Service via Unexpected memory usage](https://junglewise.ai/threats/cve-2019-1010083-pallets-project-flask-is-vulnerable-to-denial-of-service-via) (low, CVSS 3.1, published 17 Jul 2019)
- [CVE-2023-30861: Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header](https://junglewise.ai/threats/cve-2023-30861-flask-vulnerable-to-possible-disclosure-of-permanent-session) (low, CVSS 3.1, published 2 May 2023)

## Vulnerabilities per week

Nothing was published in the last eight weeks.

| Week of | Vulns | Critical | Exploited |
| --- | --- | --- | --- |
| 17 Aug 2026 | 0 | 0 | 0 |
| 24 Aug 2026 | 0 | 0 | 0 |
| 31 Aug 2026 | 0 | 0 | 0 |
| 7 Sep 2026 | 0 | 0 | 0 |
| 14 Sep 2026 | 0 | 0 | 0 |
| 21 Sep 2026 | 0 | 0 | 0 |
| 28 Sep 2026 | 0 | 0 | 0 |
| 5 Oct 2026 | 0 | 0 | 0 |
| 12 Oct 2026 | 0 | 0 | 0 |
| 19 Oct 2026 | 0 | 0 | 0 |
| 26 Oct 2026 | 0 | 0 | 0 |
| 2 Nov 2026 | 0 | 0 | 0 |
| 9 Nov 2026 | 0 | 0 | 0 |

## Other PyPI technologies

- [tensorflow (PyPI)](https://junglewise.ai/threats/technologies/pypi-tensorflow): 435 vulnerabilities
- [tensorflow-cpu (PyPI)](https://junglewise.ai/threats/technologies/tensorflow-cpu): 430 vulnerabilities
- [tensorflow-gpu (PyPI)](https://junglewise.ai/threats/technologies/tensorflow-gpu): 427 vulnerabilities
- [open-webui (PyPI)](https://junglewise.ai/threats/technologies/open-webui): 177 vulnerabilities
- [Django (PyPI)](https://junglewise.ai/threats/technologies/django): 173 vulnerabilities
- [apache-airflow (PyPI)](https://junglewise.ai/threats/technologies/apache-airflow): 159 vulnerabilities
- [pillow (PyPI)](https://junglewise.ai/threats/technologies/pillow): 125 vulnerabilities
- [praisonai (PyPI)](https://junglewise.ai/threats/technologies/pypi-praisonai): 120 vulnerabilities
- [vllm (PyPI)](https://junglewise.ai/threats/technologies/pypi-vllm): 117 vulnerabilities
- [plone (PyPI)](https://junglewise.ai/threats/technologies/pypi-plone): 101 vulnerabilities
- [mlflow (PyPI)](https://junglewise.ai/threats/technologies/mlflow): 88 vulnerabilities
- [picklescan (PyPI)](https://junglewise.ai/threats/technologies/picklescan): 86 vulnerabilities

## Sources

NVD, GitHub Security Advisories, OSV, the CISA Known Exploited Vulnerabilities catalog, FIRST EPSS and vendor advisories. Rebuilt every hour. Cite as: Junglewise Threat Intelligence, "flask (PyPI) vulnerabilities", https://junglewise.ai/threats/technologies/flask, 13 November 2026.