CVE-2021-20270
HIGHCVSS 7.5/10EPSS 2.71%
Last modified
CVE-2021-20270 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An infinite loop in SMLLexer in Pygments versions 1.5 to 2.7.3 may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the "exception" keyword.. EPSS estimates a 2.71% chance of exploitation in the next 30 days.
Description
An infinite loop in SMLLexer in Pygments versions 1.5 to 2.7.3 may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the "exception" keyword.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Pygments | Pygments | >= 1.5, <= 2.7.3 |
| Redhat | Openshift Container Platform | 3.11 |
| Redhat | Openshift Container Platform | 4.0 |
| Redhat | Openstack Platform | 10.0 |
| Redhat | Software Collections | All versions |
| Redhat | Enterprise Linux | 7.0 |
| Redhat | Enterprise Linux | 8.0 |
| Fedoraproject | Fedora | 33 |
| Debian | Debian Linux | 9.0 |
| Debian | Debian Linux | 10.0 |
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1922136Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/05/msg00003.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/05/msg00006.htmlMailing List, Third Party Advisory
- https://www.debian.org/security/2021/dsa-4889Third Party Advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlNot Applicable, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1922136Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/05/msg00003.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/05/msg00006.htmlMailing List, Third Party Advisory
- https://www.debian.org/security/2021/dsa-4889Third Party Advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlNot Applicable, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-20270?
An infinite loop in SMLLexer in Pygments versions 1.5 to 2.7.3 may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the "exception" keyword.
How severe is CVE-2021-20270?
CVE-2021-20270 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.71% probability of exploitation in the next 30 days.
How do I fix CVE-2021-20270?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-20270?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST