CVE-2021-26813

CVE-2021-26813 is a high-severity vulnerability in Markdown2 Project Markdown2 with a CVSS 3.x base score of 7.5. 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-1333.

Key facts

Description

markdown2 >=1.0.1.18, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. If an attacker provides a malicious string, it can make markdown2 processing difficult or delayed for an extended period of time.

Frequently asked questions

What is CVE-2021-26813?
markdown2 >=1.0.1.18, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. If an attacker provides a malicious string, it can make markdown2 processing difficult or delayed for an extended period of time.
How severe is CVE-2021-26813?
CVE-2021-26813 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-26813 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26813?
CVE-2021-26813 primarily affects Markdown2 Project Markdown2. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26813?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-26813 published?
CVE-2021-26813 was published on 2021-03-03 and last updated on 2026-06-17.

References

Affected products (4)

Other CWE-1333 vulnerabilities

Browse all CWE-1333 vulnerabilities →