Flask 3 lifecycle
Current status
Flask 3 is currently in standard support.
Security: 4 tracked advisories affecting this line. Details below — lifecycle and vulnerability status are separate.
Official lifecycle source: Flask PyPI releases
- Support phase
- standard support
- End of life
- Not officially published
- Latest release
- 3.0.0
- Released
- 30 Sept 2023
At a glance
- Version line
- 3
- Initial release
- 30 Sept 2023
- Lifecycle phase
- standard support
- Latest stable
- 3.0.0
- Latest release date
- 30 Sept 2023
- EOL
- Not officially published
- Risk
- low
- Releases tracked
- 8
Lifecycle timeline
Phases from published LifecyclePeriod records. Missing phases are not inferred.
Release
30 Sept 2023
standard supportcurrent
30 Sept 2023 → —
Source: Flask PyPI releases
Flask 3 is currently in standard support.
Security
Advisories affecting Flask 3 (OSV.dev evidence). Known exploited status, due dates, and ransomware use from CISA KEV when matched.
- Known vulnerabilities
- 4
- Known exploited
- 0
- Highest CVSS
- —
- CVE-2025-47278PYSEC-2026-1377
Flask uses fallback key instead of current signing key
- Affected:
- >=3.1.0,<3.1.1
- Fixed in:
- 3.1.1
- Source:
- OSV source · Advisory
- CVE-2026-27205PYSEC-2026-2151
- Affected:
- <3.1.3
- Fixed in:
- 3.1.3
- Source:
- OSV source · Advisory
- CVE-2026-27205GHSA-68rp-wp8r-4726
Flask session does not add `Vary: Cookie` header when accessed in some ways
- Affected:
- <3.1.3
- Fixed in:
- 3.1.3
- Source:
- OSV source · Advisory
- CVE-2025-47278GHSA-4grg-w6v8-c28g
Flask uses fallback key instead of current signing key
- Affected:
- >=3.1.0,<3.1.1
- Fixed in:
- 3.1.1
- Source:
- OSV source · Advisory
Latest release
Previous releases
3.0.1
18 Jan 2024
3.0.2
3 Feb 2024
3.0.3
7 Apr 2024
Release history
8 concrete releases tracked for this line.
Release activity
- Total releases
- 8
- Last 30 days
- 0
- Last 90 days
- 0
- Avg. interval
- ~125 days
- Most recent
- 30 Sept 2023
Should I use this version?
Suitable for new deployments
Flask 3 is currently supported (standard support).
Version comparison
Compact comparison against the nearest relevant release lines.
Compatibility
Evidence-backed compatibility results involving Flask 3. Only combinations CompatHub can evaluate from upstream sources are listed.
Compatible targets
Sources
Where this information comes from.
Lifecycle sources
- Flask PyPI releasesfirst party · high confidence
Official source: https://pypi.org/project/Flask/
Last verified 2 Sept 2026
- OSV.devfirst party
Official source: https://osv.dev
Verification time not recorded
- NVD (NIST)first party
Official source: https://nvd.nist.gov
Verification time not recorded
- CISA Known Exploited Vulnerabilitiesfirst party
Official source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Verification time not recorded
Release sources
- Flask PyPI releasesfirst party · high confidence
Official source: https://pypi.org/project/Flask/
Last verified 2 Sept 2026
Data coverage
Last checked = last successful upstream check. Latest source update = when upstream content last changed.
- Releases tracked
- 8
- Lifecycle periods
- 1
- EOL
- Not officially published
- Provenance records
- 2
- Data last checked
- 2 Sept 2026
- Latest source update
- 2 Sept 2026
EOL: Not officially published