GHSA-68rp-wp8r-4726

Suggest an improvement
Source
https://github.com/advisories/GHSA-68rp-wp8r-4726
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-68rp-wp8r-4726/GHSA-68rp-wp8r-4726.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-68rp-wp8r-4726
Aliases
Downstream
Related
Published
2026-02-19T20:45:41Z
Modified
2026-02-23T23:43:45.778179Z
Severity
  • 2.3 (Low) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details

When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.

The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.

  1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.
  2. The application does not set a Cache-Control header to indicate that a page is private or should not be cached.
  3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Database specific 
{
    "nvd_published_at": "2026-02-21T06:17:00Z",
    "github_reviewed_at": "2026-02-19T20:45:41Z",
    "github_reviewed": true,
    "severity": "LOW",
    "cwe_ids": [
        "CWE-524"
    ]
}
References

Affected packages

PyPI / flask

Package

Name
flask
View open source insights on deps.dev
Purl
pkg:pypi/flask

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3.1.3

Affected versions

0.*
0.1
0.2
0.3
0.3.1
0.4
0.5
0.5.1
0.5.2
0.6
0.6.1
0.7
0.7.1
0.7.2
0.8
0.8.1
0.9
0.10
0.10.1
0.11
0.11.1
0.12
0.12.1
0.12.2
0.12.3
0.12.4
0.12.5
1.*
1.0
1.0.1
1.0.2
1.0.3
1.0.4
1.1.0
1.1.1
1.1.2
1.1.3
1.1.4
2.*
2.0.0rc1
2.0.0rc2
2.0.0
2.0.1
2.0.2
2.0.3
2.1.0
2.1.1
2.1.2
2.1.3
2.2.0
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.3.0
2.3.1
2.3.2
2.3.3
3.*
3.0.0
3.0.1
3.0.2
3.0.3
3.1.0
3.1.1
3.1.2

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-68rp-wp8r-4726/GHSA-68rp-wp8r-4726.json"