CVE-2020-13258Public exploitNetwork attack vector

Reflected XSS via unencoded query-string reconstruction

Published May 21, 2020 · Updated Aug 4, 2024

Reflected XSS in Contentful's Python example app through 2020-05-21 allows remote attackers to run script in a user's browser via the api parameter. The query_string function in routes/base.py rebuilds request arguments without encoding their names or values, then templates insert the result into link href attributes. Exploitation requires a user to open a crafted URL; injected script executes in that browser context, enabling page-content changes and limited data access.

CVSS severity6.1
Medium
EPSS probability2.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Contentful's Python example app through 2020-05-21 allows remote attackers to run script in a user's browser via the api parameter. The query_string function in routes/base.py rebuilds request arguments without encoding their names or values, then templates insert the result into link href attributes. Exploitation requires a user to open a crafted URL; injected script executes in that browser context, enabling page-content changes and limited data access.

The record

CVE
CVE-2020-13258
Published
May 21, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1GitHub Security Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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')
T1189Drive-by Compromise

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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