How severe is CVE-2021-23899?

CVE-2021-23899 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-23899 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23899?

CVE-2021-23899 affects Owasp Json-sanitizer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23899?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-23899 published?

CVE-2021-23899 was published on 2021-01-13 and last updated on 2026-06-17.

CVE-2021-23899

CVE-2021-23899 is a critical-severity vulnerability in Owasp Json-sanitizer with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-611.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-611
Affected product: Owasp Json-sanitizer
Published: 2021-01-13
Last modified: 2026-06-17

Description

OWASP json-sanitizer before 1.2.2 may emit closing SCRIPT tags and CDATA section delimiters for crafted input. This allows an attacker to inject arbitrary HTML or XML into embedding documents.

Frequently asked questions

What is CVE-2021-23899?: OWASP json-sanitizer before 1.2.2 may emit closing SCRIPT tags and CDATA section delimiters for crafted input. This allows an attacker to inject arbitrary HTML or XML into embedding documents.
How severe is CVE-2021-23899?: CVE-2021-23899 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-23899 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23899?: CVE-2021-23899 affects Owasp Json-sanitizer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23899?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-23899 published?: CVE-2021-23899 was published on 2021-01-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:owasp:json-sanitizer:*:*:*:*:*:*:*:*

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