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Flask 0.9 lifecycle

Current status

standard supportlow

Flask 0.9 is currently in standard support.

Security: 7 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
0.9
Released
1 Jul 2012

At a glance

Version line
0.9
Initial release
1 Jul 2012
Lifecycle phase
standard support
Latest stable
0.9
Latest release date
1 Jul 2012
EOL
Not officially published
Risk
low
Releases tracked
1

Lifecycle timeline

Phases from published LifecyclePeriod records. Missing phases are not inferred.

  1. Release

    1 Jul 2012

  2. standard supportcurrent

    1 Jul 2012 → —

    Source: Flask PyPI releases

Flask 0.9 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 0.9

Supported

Supported upgrade options

Open full upgrade planner for Flask 0.9 →

Security

Advisories affecting Flask 0.9 (OSV.dev evidence). Known exploited status, due dates, and ransomware use from CISA KEV when matched.

Known vulnerabilities
7
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
  • CVE-2019-1010083GHSA-5wv5-4vpf-pj6m

    Pallets Project Flask is vulnerable to Denial of Service via Unexpected memory usage

    Affected:
    <1.0
    Fixed in:
    1.0
    Source:
    OSV source · Advisory
  • CVE-2019-1010083PYSEC-2019-179
    Affected:
    <1.0
    Fixed in:
    1.0
    Source:
    OSV source · Advisory
  • CVE-2018-1000656GHSA-562c-5r94-xh97

    Flask is vulnerable to Denial of Service via incorrect encoding of JSON data

    Affected:
    <0.12.3
    Fixed in:
    0.12.3
    Source:
    OSV source · Advisory
  • CVE-2018-1000656PYSEC-2018-66
    Affected:
    <0.12.3
    Fixed in:
    0.12.3
    Source:
    OSV source · Advisory

Latest release

0.9

Released 1 Jul 2012 · stable

https://pypi.org/pypi/Flask/0.9/json

Release history

1 concrete release tracked for this line.

VersionRelease dateChannelSource
0.91 Jul 2012stableSource

Release activity

Total releases
1
Last 30 days
0
Last 90 days
0
Most recent
1 Jul 2012

Should I use this version?

Suitable for new deployments

Flask 0.9 is currently supported (standard support).

Version comparison

Compact comparison against the nearest relevant release lines.

0.93
Statusstandard supportstandard support
Latest release0.93.0.0
EOLNot publishedNot published
Risklowlow

Compatibility

Evidence-backed compatibility results involving Flask 0.9. Only combinations CompatHub can evaluate from upstream sources are listed.

Compatible targets

Open Compatibility Explorer →

Sources

Where this information comes from.

Lifecycle sources

Release sources

Data coverage

Last checked = last successful upstream check. Latest source update = when upstream content last changed.

Releases tracked
1
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

Other Flask versions