How severe is CVE-2021-33558?

CVE-2021-33558 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 high, integrity none, and availability none.

Is CVE-2021-33558 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33558?

CVE-2021-33558 affects Boa. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33558?

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-2021-33558 published?

CVE-2021-33558 was published on 2021-05-27 and last updated on 2026-06-17.

CVE-2021-33558

CVE-2021-33558 is a high-severity vulnerability in Boa with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 10% places it in the 95th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 10% (95th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Boa
Published: 2021-05-27
Last modified: 2026-06-17

Description

Boa 0.94.13 allows remote attackers to obtain sensitive information via a misconfiguration involving backup.html, preview.html, js/log.js, log.html, email.html, online-users.html, and config.js. NOTE: multiple third parties report that this is a site-specific issue because those files are not part of Boa.

Frequently asked questions

What is CVE-2021-33558?: Boa 0.94.13 allows remote attackers to obtain sensitive information via a misconfiguration involving backup.html, preview.html, js/log.js, log.html, email.html, online-users.html, and config.js. NOTE: multiple third parties report that this is a site-specific issue because those files are not part of Boa.
How severe is CVE-2021-33558?: CVE-2021-33558 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 high, integrity none, and availability none.
Is CVE-2021-33558 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33558?: CVE-2021-33558 affects Boa. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33558?: 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-2021-33558 published?: CVE-2021-33558 was published on 2021-05-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:boa:boa:0.94.13:*:*:*:*:*:*:*

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