How severe is CVE-2021-27918?

CVE-2021-27918 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-2021-27918 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27918?

CVE-2021-27918 affects Golang Go. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27918?

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-2021-27918 published?

CVE-2021-27918 was published on 2021-03-11 and last updated on 2026-06-17.

CVE-2021-27918

CVE-2021-27918 is a high-severity vulnerability in Golang Go 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-835.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 3% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Golang Go
Published: 2021-03-11
Last modified: 2026-06-17

Description

encoding/xml in Go before 1.15.9 and 1.16.x before 1.16.1 has an infinite loop if a custom TokenReader (for xml.NewTokenDecoder) returns EOF in the middle of an element. This can occur in the Decode, DecodeElement, or Skip method.

Frequently asked questions

What is CVE-2021-27918?: encoding/xml in Go before 1.15.9 and 1.16.x before 1.16.1 has an infinite loop if a custom TokenReader (for xml.NewTokenDecoder) returns EOF in the middle of an element. This can occur in the Decode, DecodeElement, or Skip method.
How severe is CVE-2021-27918?: CVE-2021-27918 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-2021-27918 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27918?: CVE-2021-27918 affects Golang Go. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27918?: 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-2021-27918 published?: CVE-2021-27918 was published on 2021-03-11 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*

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