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Vulnerability Database · PyPI · Package report

flask: vulnerability history, versions and safety

flask is a package in the PyPI ecosystem. Vulert records 10 vulnerabilities for it across 64 releases, from Aug 2018 to Jul 2026. Each vulnerability names the versions it affects, the fixed version to move to, and a workaround where no fix has been published.

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10 vulnerabilities recorded H3 L2 U5
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0 with no fix published

Every vulnerability has a patched version to move to.

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3 in the last 12 months

Most recent disclosure 07 Jul 2026.

See the disclosure history →
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0 malicious-package vulnerabilities

No published version shipped hostile code.

See all flask vulnerabilities

Vulert verdict on flask 3.1.3 i

Updated on 23 Oct 2026

Action needed: 3.1.3 has 1 known vulnerability, but every one of them has a fix. Upgrade to the version listed below and you are clear.

Package health score 83/100
  • Security Minor issues
  • Maintenance Sustainable
  • Popularity Key ecosystem project
  • Community Active

What to do: Upgrade to the version that resolves each vulnerability below. Fix it, then keep watch: this version is affected today, and the next one may be too — Vulert alerts you when a new vulnerability lands. Monitor it with Vulert →

  • Current release 3.1.3 — affected i
  • Vulnerabilities on record 10 over 7 years · 3 in the last year i
  • Latest disclosure 07 Jul 2026 i
  • Highest CVSS 7.5 i
  • With no published fix 0 i
  • Depended on by 12,834 packages i
  • Stars 74,944 i
  • OpenSSF scorecard 7/10 i
  • Last release 8 months ago i
  • Licence BSD-3-Clause i

Version list, release dates, licence and dependants published by PyPI, refreshed 22 Oct 2026. Licence information is not legal advice.

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01 Versions

Which versions are affected

Every version Vulert tracks for flask, newest first, with the vulnerabilities recorded against each one. A version showing none has no vulnerability in the Vulert database — open it for the full picture on that release.

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Version Released Vulert vulnerabilities Licence Fix published Details
3.1.3 19 Feb 2026 U1 BSD-3-Clause Yes Details →
3.1.2 19 Aug 2025 L1 U1 BSD-3-Clause Yes Details →
3.1.1 13 May 2025 L1 U1 BSD-3-Clause Yes Details →
3.1.0 13 Nov 2024 L2 U2 non-standard Yes Details →
3.0.3 07 Apr 2024 L1 U1 non-standard Yes Details →
3.0.2 03 Feb 2024 L1 U1 non-standard Yes Details →
3.0.1 18 Jan 2024 L1 U1 non-standard Yes Details →
3.0.0 30 Sep 2023 L1 U1 non-standard Yes Details →
2.3.3 21 Aug 2023 L1 U1 non-standard Yes Details →
2.2.5 02 May 2023 L1 U1 BSD-3-Clause Yes Details →
2.3.2 01 May 2023 L1 U1 BSD-3-Clause Yes Details →
2.3.1 25 Apr 2023 H1 L1 U2 BSD-3-Clause Yes Details →
2.3.0 25 Apr 2023 H1 L1 U2 BSD-3-Clause Yes Details →
2.2.4 25 Apr 2023 L1 U2 BSD-3-Clause Yes Details →
2.2.3 15 Feb 2023 L1 U2 BSD-3-Clause Yes Details →
2.2.2 08 Aug 2022 L1 U2 BSD-3-Clause Yes Details →
2.2.1 03 Aug 2022 L1 U2 BSD-3-Clause Yes Details →
2.2.0 02 Aug 2022 L1 U2 BSD-3-Clause Yes Details →
2.1.3 13 Jul 2022 L1 U2 BSD-3-Clause Yes Details →
2.1.2 28 Apr 2022 L1 U2 BSD-3-Clause Yes Details →
2.1.1 30 Mar 2022 L1 U2 BSD-3-Clause Yes Details →
2.1.0 28 Mar 2022 L1 U2 BSD-3-Clause Yes Details →
2.0.3 14 Feb 2022 L1 U2 BSD-3-Clause Yes Details →
2.0.2 04 Oct 2021 L1 U2 BSD-3-Clause Yes Details →
2.0.1 21 May 2021 L1 U2 BSD-3-Clause Yes Details →
1.1.4 14 May 2021 L1 U2 BSD-3-Clause Yes Details →
1.1.3 13 May 2021 L1 U2 BSD-3-Clause Yes Details →
2.0.0 11 May 2021 L1 U2 BSD-3-Clause Yes Details →
2.0.0rc2 03 May 2021 L1 U2 BSD-3-Clause Yes Details →
2.0.0rc1 16 Apr 2021 L1 U2 BSD-3-Clause Yes Details →
1.1.2 03 Apr 2020 L1 U2 BSD-3-Clause Yes Details →
0.12.5 10 Feb 2020 H1 L1 U3 non-standard Yes Details →
1.1.1 08 Jul 2019 L1 U2 BSD-3-Clause Yes Details →
1.1.0 04 Jul 2019 L1 U2 BSD-3-Clause Yes Details →
1.0.4 04 Jul 2019 L1 U2 BSD-3-Clause Yes Details →
1.0.3 17 May 2019 L1 U2 non-standard Yes Details →
1.0.2 02 May 2018 L1 U2 non-standard Yes Details →
1.0.1 30 Apr 2018 L1 U2 non-standard Yes Details →
0.12.4 30 Apr 2018 H1 L1 U3 non-standard Yes Details →
1.0.0 26 Apr 2018 L1 U2 non-standard Yes Details →
0.12.3 26 Apr 2018 H1 L1 U3 non-standard Yes Details →
0.12.2 16 May 2017 H2 L1 U4 non-standard Yes Details →
0.12.1 31 Mar 2017 H2 L1 U4 non-standard Yes Details →
0.12.0 21 Dec 2016 H2 L1 U4 non-standard Yes Details →
0.11.1 07 Jun 2016 H2 L1 U4 non-standard Yes Details →
0.11.0 29 May 2016 H2 L1 U4 non-standard Yes Details →
0.10.1 14 Jun 2013 H2 L1 U4 non-standard Yes Details →
0.10.0 13 Jun 2013 H2 L1 U4 non-standard Yes Details →
0.9.0 01 Jul 2012 H2 L1 U4 non-standard Yes Details →
0.8.1 01 Jul 2012 H2 L1 U4 non-standard Yes Details →
0.8.0 29 Sep 2011 H2 L1 U4 non-standard Yes Details →
0.7.2 06 Jul 2011 H2 L1 U4 non-standard Yes Details →
0.7.1 29 Jun 2011 H2 L1 U4 non-standard Yes Details →
0.7.0 28 Jun 2011 H2 L1 U4 non-standard Yes Details →
0.6.1 31 Dec 2010 H2 L1 U4 non-standard Yes Details →
0.6.0 27 Jul 2010 H2 L1 U4 non-standard Yes Details →
0.5.2 15 Jul 2010 H2 L1 U4 non-standard Yes Details →
0.5.1 06 Jul 2010 H2 L1 U4 non-standard Yes Details →
0.5.0 06 Jul 2010 H2 L1 U4 non-standard Yes Details →
0.4.0 18 Jun 2010 H2 L1 U4 non-standard Yes Details →
0.3.1 28 May 2010 H2 L1 U4 non-standard Yes Details →
0.3.0 28 May 2010 H2 L1 U4 non-standard Yes Details →
0.2.0 12 May 2010 H2 L1 U4 non-standard Yes Details →
0.1.0 16 Apr 2010 H2 L1 U4 non-standard Yes Details →

All 64 versions Vulert tracks for this package. Severity counts are the vulnerabilities recorded against that exact release.

02 Disclosure history

How often vulnerabilities are recorded

  • 2018 2
  • 2019 2
  • 2023 2
  • 2025 1
  • 2026 3

Counted by the year Vulert recorded each vulnerability — the same date the table below shows as disclosed. 3 of the 10 were recorded in the last 12 months.

03 Vulnerabilities

Recorded vulnerabilities for flask

The 5 most severe of 10 vulnerabilities recorded for this package

Search all 10 in the database →
Vulnerability Severity Fixed version ↓ Disclosed ↓
CVE-2018-1000656: Flask - Denial of Service via incorrect encoding of JSON data 7.5 high 0.12.3 23 Aug 2018
CVE-2019-1010083: Pallets Project Flask Denial of Service via Unexpected memory usage 7.5 high 1.0 19 Jul 2019
CVE-2023-30861: Flask - Possible Disclosure of Permanent Session Cookie 7.5 high 2.3.2 01 May 2023
CVE-2026-27205: Flask Vulnerability in Session Handling Leading to Cache Exposure 4.3 medium 3.1.3 21 Feb 2026
CVE-2026-27205: Flask Vulnerability in Session Handling Leading to Cache Misconfiguration 2.3 low 3.1.3 19 Feb 2026

Vulnerability wrong, a fix missing, or a package we should cover? Report it and we will fix the record. Report Vulnerability Provide Feedback

Updated: 23/Oct/2026 · Vulnerabilities in our DB: 524315

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Questions

About flask

Is flask safe to use?

Vulert records 10 vulnerabilities for flask in PyPI: 0 critical, 3 high, 0 medium and 2 low, plus 5 not yet rated. Every one of them has a published fix, so the practical answer is to run a supported release and keep it patched.

What is flask's Vulert package health score?

Vulert scores flask 83/100, which reads as in good shape. The score weighs the vulnerability record (40), maintenance and release cadence (25), adoption from dependents and stars (20) and community signals such as the OpenSSF scorecard and forks (15).

Is the latest version of flask affected?

Yes. 3.1.3, the version you would install today, has 1 known vulnerability, and every one of them has a published fix. Upgrade to the version listed for each.

Which version of flask should I use?

3.1.3 is the version Vulert recommends for the affected releases. The version table above lists every release with the vulnerabilities recorded against it, so you can confirm the range you actually run.

How many vulnerabilities does flask have?

10 vulnerabilities are recorded for flask in the PyPI ecosystem: 0 critical, 3 high, 0 medium and 2 low, plus 5 not yet rated. The ledger on this page lists the same counts next to the date of the most recent disclosure.

How often are new flask vulnerabilities disclosed?

3 vulnerabilities were recorded for flask in the last 12 months, and the oldest entry in this database dates to 20 Aug 2018. Recency matters more than a lifetime total: it shows how actively new issues are being disclosed for the package you are considering.

Which versions of flask are affected?

Each vulnerability on this page lists the affected version range and the fixed version to move to. Open the vulnerability for the version you actually run — fixes are specific to a release line, not to the package as a whole.

How do I monitor flask for upcoming vulnerabilities?

Upload the manifest or SBOM for your application at vulert.com/scanner and Vulert keeps checking the flask version you actually run against new disclosures, then alerts you when one affects it. There is no installation and no source-code access required.