Flask 1 lifecycle
Current status
Flask 1 is currently in standard support.
Security: 3 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
- 1.0.1
- Released
- 30 Apr 2018
At a glance
- Version line
- 1
- Initial release
- 26 Apr 2018
- Lifecycle phase
- standard support
- Latest stable
- 1.0.1
- Latest release date
- 30 Apr 2018
- EOL
- Not officially published
- Risk
- low
- Releases tracked
- 10
Lifecycle timeline
Phases from published LifecyclePeriod records. Missing phases are not inferred.
Release
26 Apr 2018
standard supportcurrent
26 Apr 2018 → —
Source: Flask PyPI releases
Flask 1 is currently in standard support.
Upgrade options
Newer supported Flask version lines from CompatHub lifecycle data. Compatibility and security context use existing evidence only.
You are on Flask 1
Supported
Supported upgrade options
- Flask 3Upgrade planner →Supported· 2 major versions newer
- Flask 2Upgrade planner →Supported· 1 major version newer
Security
Advisories affecting Flask 1 (OSV.dev evidence). Known exploited status, due dates, and ransomware use from CISA KEV when matched.
- Known vulnerabilities
- 3
- Known exploited
- 0
- Highest CVSS
- —
- 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-2023-30861GHSA-m2qf-hxjv-5gpq
Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header
- Affected:
- <2.2.5
- Fixed in:
- 2.2.5
- Source:
- OSV source · Advisory
Latest release
Previous releases
1.0.2
2 May 2018
1.0.3
17 May 2019
1.0
26 Apr 2018
Release history
10 concrete releases tracked for this line.
| Version | Release date | Channel | Source |
|---|---|---|---|
| 1.0 | 26 Apr 2018 | stable | Source |
| 1.0.1 | 30 Apr 2018 | stable | Source |
| 1.0.2 | 2 May 2018 | stable | Source |
| 1.0.3 | 17 May 2019 | stable | Source |
| 1.0.4 | 4 Jul 2019 | stable | Source |
| 1.1.0 | 4 Jul 2019 | stable | Source |
| 1.1.1 | 8 Jul 2019 | stable | Source |
| 1.1.2 | 3 Apr 2020 | stable | Source |
| 1.1.3 | 13 May 2021 | stable | Source |
| 1.1.4 | 14 May 2021 | stable | Source |
Release activity
- Total releases
- 10
- Last 30 days
- 0
- Last 90 days
- 0
- Avg. interval
- ~124 days
- Most recent
- 30 Apr 2018
Should I use this version?
Suitable for new deployments
Flask 1 is currently supported (standard support).
Version comparison
Compact comparison against the nearest relevant release lines.
Compatibility
Evidence-backed compatibility results involving Flask 1. 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
- 10
- 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