How severe is CVE-2021-33580?

CVE-2021-33580 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-2021-33580 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33580?

CVE-2021-33580 affects Apache Roller. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33580?

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-2021-33580 published?

CVE-2021-33580 was published on 2021-08-18 and last updated on 2026-06-17.

CVE-2021-33580

CVE-2021-33580 is a high-severity vulnerability in Apache Roller 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-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Apache Roller
Published: 2021-08-18
Last modified: 2026-06-17

Description

User controlled `request.getHeader("Referer")`, `request.getRequestURL()` and `request.getQueryString()` are used to build and run a regex expression. The attacker doesn't have to use a browser and may send a specially crafted Referer header programmatically. Since the attacker controls the string and the regex pattern he may cause a ReDoS by regex catastrophic backtracking on the server side. This problem has been fixed in Roller 6.0.2.

Frequently asked questions

What is CVE-2021-33580?: User controlled `request.getHeader("Referer")`, `request.getRequestURL()` and `request.getQueryString()` are used to build and run a regex expression. The attacker doesn't have to use a browser and may send a specially crafted Referer header programmatically. Since the attacker controls the string and the regex pattern he may cause a ReDoS by regex catastrophic backtracking on the server side. This problem has been fixed in Roller 6.0.2.
How severe is CVE-2021-33580?: CVE-2021-33580 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-2021-33580 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33580?: CVE-2021-33580 affects Apache Roller. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33580?: 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-2021-33580 published?: CVE-2021-33580 was published on 2021-08-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:roller:*:*:*:*:*:*:*:*

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