How severe is CVE-2021-27737?

CVE-2021-27737 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-2021-27737 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27737?

CVE-2021-27737 affects Apache Traffic Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27737?

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-2021-27737 published?

CVE-2021-27737 was published on 2021-05-14 and last updated on 2026-06-17.

CVE-2021-27737

CVE-2021-27737 is a high-severity vulnerability in Apache Traffic Server 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.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Apache Traffic Server
Published: 2021-05-14
Last modified: 2026-06-17

Description

Apache Traffic Server 9.0.0 is vulnerable to a remote DOS attack on the experimental Slicer plugin.

Frequently asked questions

What is CVE-2021-27737?: Apache Traffic Server 9.0.0 is vulnerable to a remote DOS attack on the experimental Slicer plugin.
How severe is CVE-2021-27737?: CVE-2021-27737 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-2021-27737 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27737?: CVE-2021-27737 affects Apache Traffic Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27737?: 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-2021-27737 published?: CVE-2021-27737 was published on 2021-05-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:traffic_server:9.0.0:-:*:*:*:*:*:*

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