CVE-2020-13973Public exploitNetwork attack vector

Cross-site scripting via script-end parser confusion

Published Jun 9, 2020 · Updated Aug 4, 2024

Cross-site scripting in OWASP json-sanitizer before 1.2.1 allows remote attackers to execute JavaScript via crafted JSON output. JsonSanitizer.sanitizeString fails to neutralize script-opening and comment sequences that drive the HTML parser into an escaped state, allowing a later end tag to terminate the script element. Exploitation requires attacker control over both the input JSON and content adjacent to the script element, and execution occurs in a user’s browser.

CVSS severity6.1
Medium
EPSS probability1.12%
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 OWASP json-sanitizer before 1.2.1 allows remote attackers to execute JavaScript via crafted JSON output. JsonSanitizer.sanitizeString fails to neutralize script-opening and comment sequences that drive the HTML parser into an escaped state, allowing a later end tag to terminate the script element. Exploitation requires attacker control over both the input JSON and content adjacent to the script element, and execution occurs in a user’s browser.

The record

CVE
CVE-2020-13973
Published
Jun 9, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 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

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS: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')
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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