What’s Vulnerable › Vulnerabilities

CVE-2021-32723: Regular Expression Denial of Service (ReDoS) in Prism

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-28 · updated 2026-06-17
• Weakness: CWE-400

Description

Prism is a syntax highlighting library. Some languages before 1.24.0 are vulnerable to Regular Expression Denial of Service (ReDoS). When Prism is used to highlight untrusted (user-given) text, an attacker can craft a string that will take a very very long time to highlight. This problem has been fixed in Prism v1.24. As a workaround, do not use ASCIIDoc or ERB to highlight untrusted text. Other languages are not affected and can be used to highlight untrusted text.

Affected products

• Oracle Corporation Application Express: before 21.1.4 — fixed in 21.1.4
• PrismJS prism: before 1.24.0 — fixed in 1.24.0

How to fix

Upgrade to a fixed version: Oracle Corporation Application Express 21.1.4; PrismJS prism 1.24.0. Check the vendor advisory for mitigations.

References

• https://github.com/PrismJS/prism/pull/2688
• https://github.com/PrismJS/prism/pull/2774
• https://github.com/PrismJS/prism/security/advisories/GHSA-gj77-59wh-66hg
• https://www.oracle.com/security-alerts/cpujan2022.html
• https://github.com/PrismJS/prism/pull/2688
• https://github.com/PrismJS/prism/pull/2774
• https://github.com/PrismJS/prism/security/advisories/GHSA-gj77-59wh-66hg
• https://www.oracle.com/security-alerts/cpujan2022.html

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