# flask (PyPI) vulnerabilities

5 known vulnerabilities (1 high, 2 low), with the versions each affects and the releases that fix them.

## At a glance

- Latest release: not known (cve.now hasn't read this package's releases)
- Newest unaffected release: not known without release data
- Registry: https://pypi.org/project/flask/

## Advisories (5)

### [CVE-2026-27205](https://cve.now/CVE-2026-27205): Flask session does not add \`Vary: Cookie\` header when accessed in some ways

- Severity: Low 2.3
- Published: Feb 21, 2026
- Affected: fixed in 3.1.3.

### [CVE-2025-47278](https://cve.now/CVE-2025-47278): Flask uses fallback key instead of current signing key

- Severity: Low 1.8
- Published: May 13, 2025
- Affected: from 3.1.0, fixed in 3.1.1.

### [CVE-2023-30861](https://cve.now/CVE-2023-30861): Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header

- Severity: High 7.5
- Published: May 2, 2023
- Affected: fixed in 2.2.5; from 2.3.0, fixed in 2.3.2; from 2.3.0, fixed in 2.3.2; fixed in 2.2.5.

### [CVE-2019-1010083](https://cve.now/CVE-2019-1010083): The Pallets Project Flask before 1.0 is affected by: unexpected memory usage.

- Severity: Unrated
- Published: Jul 17, 2019
- Affected: fixed in 1.0.

### [CVE-2018-1000656](https://cve.now/CVE-2018-1000656): The Pallets Project flask version Before 0.12.3 contains a CWE-20: Improper Input Validation vulnerability in flask that can result in…

- Severity: Unrated
- Published: Aug 20, 2018
- Affected: fixed in 0.12.3.

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