How severe is CVE-2020-10518?

CVE-2020-10518 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-10518 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-10518?

CVE-2020-10518 affects Github. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-10518?

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-2020-10518 published?

CVE-2020-10518 was published on 2020-08-27 and last updated on 2026-06-17.

CVE-2020-10518

CVE-2020-10518 is a high-severity vulnerability in Github with a CVSS 3.x base score of 8.8. 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-77.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-77
Affected product: Github
Published: 2020-08-27
Last modified: 2026-06-17

Description

A remote code execution vulnerability was identified in GitHub Enterprise Server that could be exploited when building a GitHub Pages site. User-controlled configuration of the underlying parsers used by GitHub Pages were not sufficiently restricted and made it possible to execute commands on the GitHub Enterprise Server instance. To exploit this vulnerability, an attacker would need permission to create and build a GitHub Pages site on the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 2.22 and was fixed in 2.21.6, 2.20.15, and 2.19.21. The underlying issues contributing to this vulnerability were identified both internally and through the GitHub Security Bug Bounty program.

Frequently asked questions

What is CVE-2020-10518?: A remote code execution vulnerability was identified in GitHub Enterprise Server that could be exploited when building a GitHub Pages site. User-controlled configuration of the underlying parsers used by GitHub Pages were not sufficiently restricted and made it possible to execute commands on the GitHub Enterprise Server instance. To exploit this vulnerability, an attacker would need permission to create and build a GitHub Pages site on the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 2.22 and was fixed in 2.21.6, 2.20.15, and 2.19.21. The underlying issues contributing to this vulnerability were identified both internally and through the GitHub Security Bug Bounty program.
How severe is CVE-2020-10518?: CVE-2020-10518 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-10518 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-10518?: CVE-2020-10518 affects Github. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-10518?: 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-2020-10518 published?: CVE-2020-10518 was published on 2020-08-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:github:github:*:*:*:*:enterprise:*:*:*

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