How severe is CVE-2020-21524?

CVE-2020-21524 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2020-21524 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-21524?

CVE-2020-21524 affects Halo. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-21524?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-21524 published?

CVE-2020-21524 was published on 2020-09-30 and last updated on 2026-06-17.

CVE-2020-21524

CVE-2020-21524 is a critical-severity vulnerability in Halo with a CVSS 3.x base score of 9.1. 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-611.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-611
Affected product: Halo
Published: 2020-09-30
Last modified: 2026-06-17

Description

There is a XML external entity (XXE) vulnerability in halo v1.1.3, The function of importing other blogs in the background(/api/admin/migrations/wordpress) needs to parse the xml file, but it is not used for security defense, This vulnerability can detect the intranet, read files, enable ddos attacks, etc. exp:https://github.com/halo-dev/halo/issues/423

Frequently asked questions

What is CVE-2020-21524?: There is a XML external entity (XXE) vulnerability in halo v1.1.3, The function of importing other blogs in the background(/api/admin/migrations/wordpress) needs to parse the xml file, but it is not used for security defense, This vulnerability can detect the intranet, read files, enable ddos attacks, etc. exp:https://github.com/halo-dev/halo/issues/423
How severe is CVE-2020-21524?: CVE-2020-21524 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2020-21524 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-21524?: CVE-2020-21524 affects Halo. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-21524?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-21524 published?: CVE-2020-21524 was published on 2020-09-30 and last updated on 2026-06-17.

References

https://github.com/halo-dev/halo/issues/423

Affected products (1)

cpe:2.3:a:halo:halo:1.1.3:-:*:*:*:*:*:*

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