How severe is CVE-2021-42009?

CVE-2021-42009 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-42009 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42009?

CVE-2021-42009 affects Apache Traffic Control. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42009?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-42009 published?

CVE-2021-42009 was published on 2021-10-12 and last updated on 2026-06-17.

CVE-2021-42009

CVE-2021-42009 is a medium-severity vulnerability in Apache Traffic Control with a CVSS 3.x base score of 4.3. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.0
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Apache Traffic Control
Published: 2021-10-12
Last modified: 2026-06-17

Description

An authenticated Apache Traffic Control Traffic Ops user with Portal-level privileges can send a request with a specially-crafted email subject to the /deliveryservices/request Traffic Ops endpoint to send an email, from the Traffic Ops server, with an arbitrary body to an arbitrary email address. Apache Traffic Control 5.1.x users should upgrade to 5.1.3 or 6.0.0. 4.1.x users should upgrade to 5.1.3.

Frequently asked questions

What is CVE-2021-42009?: An authenticated Apache Traffic Control Traffic Ops user with Portal-level privileges can send a request with a specially-crafted email subject to the /deliveryservices/request Traffic Ops endpoint to send an email, from the Traffic Ops server, with an arbitrary body to an arbitrary email address. Apache Traffic Control 5.1.x users should upgrade to 5.1.3 or 6.0.0. 4.1.x users should upgrade to 5.1.3.
How severe is CVE-2021-42009?: CVE-2021-42009 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-42009 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42009?: CVE-2021-42009 affects Apache Traffic Control. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42009?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-42009 published?: CVE-2021-42009 was published on 2021-10-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:traffic_control:*:*:*:*:*:*:*:*

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