CVE-2026-48587: Django Has_vary_header May Expose Cached Responses Vulnerability

LOW
Advisory Identifier: GHSA-923m-gv2p-w5qp
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CVSS 3.1
CWE-1023
Published
Advisory Summary

CVE-2026-48587 is a LOW (CVSS 3.1) has_vary_header may expose cached responses vulnerability (CWE-1023: Incomplete Comparison with Missing Factors) affecting Django libraries in the PyPI ecosystem. The issue involves has_vary_header may expose cached responses when vary values contain whitespace. Remediation is available by upgrading affected packages to version 5.2.15, 6.0.6.

CVE-2026-48587 at a Glance

CVE Identifier CVE-2026-48587
GHSA Identifier GHSA-923m-gv2p-w5qp
Severity LOW
CVSS v3.1 Base Score 3.1
CWE Classification CWE-1023: Incomplete Comparison with Missing Factors
Affected Product Django
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 3.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-48587

To remediate this vulnerability, upgrade all affected Django dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

django fixed: 5.2.15 
pip install django>=5.2.15
django fixed: 6.0.6 
pip install django>=6.0.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show django

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-48587, inspect your installed packages using pip:

pip show django

Analyze the terminal output to locate any version of Django in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.2.15), your application is affected.

Note: The pip show django command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1023: Incomplete Comparison with Missing Factors, where the product performs a comparison between entities that must consider multiple factors or characteristics of each entity, but the comparison does not include one or more of these factors. In Django, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An issue was discovered in Django 5.2 before 5.2.15 and 6.0 before 6.0.6. `django.utils.cache.has_vary_header()` in Django does not strip leading or trailing whitespace from `Vary` response header values before comparison, which allows remote attackers to read cached responses via requests to URLs whose responses contain whitespace-padded Vary header values. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Navid Rezazadeh for reporting this issue.

CVE-2026-48587 Affected Django Versions

2 component(s)
Fixed Versions:
5.2.156.0.6
Product / Package Ecosystem Affected Versions Fixed Version
django
pypi/django
PyPI
< 5.2.15
5.2.15
django
pypi/django
PyPI
≥ 6.0.0
< 6.0.6
6.0.6

References

NVD — CVE-2026-48587 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-48587
Security Fix Commit FIX COMMIT
https://github.com/django/django/commit/1721035a72624aad7b38dd19b14013efd94b24b8
Security Fix Commit FIX COMMIT
https://github.com/django/django/commit/42aa0b3364d312e7c6472258d8b0e9c0277fbf22
Security Fix Commit FIX COMMIT
https://github.com/django/django/commit/9b62b0af71a14c657d19d95371630ba839e83d9a
Django Release RELEASE
https://docs.djangoproject.com/en/dev/releases/security
Django Source Repository REPOSITORY
https://github.com/django/django
Django Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/django/PYSEC-2026-198.yaml
groups.google.com/g/django-announce WEB
https://groups.google.com/g/django-announce
Django Release RELEASE
https://www.djangoproject.com/weblog/2026/jun/03/security-releases

Frequently Asked Questions

What is CVE-2026-48587?
CVE-2026-48587 is a security vulnerability in Django involving has_vary_header may expose cached responses when Vary values contain whitespace under CWE-1023: Incomplete Comparison with Missing Factors.
Which Django versions are affected?
Affected versions include releases prior to 5.2.15, 6.0.6 across affected packages: django.
What version fixes CVE-2026-48587?
Upgrading to 5.2.15, 6.0.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is django affected?
Yes, django is affected in releases prior to 5.2.15, 6.0.6. Upgrade your dependency to 5.2.15, 6.0.6 or later.
What is the CVSS score of CVE-2026-48587?
CVE-2026-48587 has a CVSS v3.1 base score of 3.1 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-48587?
CVE-2026-48587 is classified under CWE-1023: Incomplete Comparison with Missing Factors (The product performs a comparison between entities that must consider multiple factors or characteristics of each entity, but the comparison does not include one or more of these factors.).
How can I check PyPI dependencies for CVE-2026-48587?
Run the dependency tree command: 'pip show django'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-923m-gv2p-w5qp",
  "modified" : "2026-08-07T19:56:56Z",
  "published" : "2026-06-03T15:30:43Z",
  "aliases" : [ "CVE-2026-48587" ],
  "summary" : "Django: has_vary_header may expose cached responses when Vary values contain whitespace",
  "details" : "An issue was discovered in Django 5.2 before 5.2.15 and 6.0 before 6.0.6.\n`django.utils.cache.has_vary_header()` in Django does not strip leading or trailing whitespace from `Vary` response header values before comparison, which allows remote attackers to read cached responses via requests to URLs whose responses contain whitespace-padded Vary header values.\nEarlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected.\nDjango would like to thank Navid Rezazadeh for reporting this issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "django"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.2.15"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "django"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.0.0"
      }, {
        "fixed" : "6.0.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-48587"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django/django/commit/1721035a72624aad7b38dd19b14013efd94b24b8"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django/django/commit/42aa0b3364d312e7c6472258d8b0e9c0277fbf22"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django/django/commit/9b62b0af71a14c657d19d95371630ba839e83d9a"
  }, {
    "type" : "WEB",
    "url" : "https://docs.djangoproject.com/en/dev/releases/security"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/django/django"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/django/PYSEC-2026-198.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/django-announce"
  }, {
    "type" : "WEB",
    "url" : "https://www.djangoproject.com/weblog/2026/jun/03/security-releases"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1023" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-07T19:56:56Z",
    "nvd_published_at" : "2026-06-03T14:16:44Z"
  }
}