CVE-2024-21520Public exploitNetwork attack vector

Cross-site scripting via unescaped long header

Published Jun 26, 2024 · Updated Dec 31, 2024

Cross-site scripting in Django REST framework before 3.15.2 allows remote attackers to inject script through long browsable-API headers. The break_long_headers filter marks generated HTML as safe after splitting an unescaped header value and inserting br elements, so attacker-controlled markup remains executable. Exploitation requires an application to place attacker-controlled data in a header longer than 160 characters and a user to view that response in the browsable API; script then runs in that user’s browser context.

CVSS severity6.1
Medium
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Django REST framework before 3.15.2 allows remote attackers to inject script through long browsable-API headers. The break_long_headers filter marks generated HTML as safe after splitting an unescaped header value and inserting br elements, so attacker-controlled markup remains executable. Exploitation requires an application to place attacker-controlled data in a header longer than 160 characters and a user to view that response in the browsable API; script then runs in that user’s browser context.

The record

CVE
CVE-2024-21520
Published
Jun 26, 2024
Updated
Dec 31, 2024
Vendor
Django REST framework
Product
Django REST framework
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 26, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 31, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.15.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Django REST framework · Django REST frameworkversion=0 <3.15.2

Published CVSS scores

6.1UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
2.1UbuntuCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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