How severe is CVE-2021-22161?

CVE-2021-22161 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-22161 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-22161?

CVE-2021-22161 affects Openwrt. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-22161?

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

When was CVE-2021-22161 published?

CVE-2021-22161 was published on 2021-02-07 and last updated on 2026-06-17.

CVE-2021-22161

CVE-2021-22161 is a medium-severity vulnerability in Openwrt with a CVSS 3.x base score of 6.5. 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-835.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 3.3
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Openwrt
Published: 2021-02-07
Last modified: 2026-06-17

Description

In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates excessive network traffic between an affected device and its upstream ISP's router. This occurs when a link prefix route points to a point-to-point link, a destination IPv6 address belongs to the prefix and is not a local IPv6 address, and a router advertisement is received with at least one global unique IPv6 prefix for which the on-link flag is set. This affects the netifd and odhcp6c packages.

Frequently asked questions

What is CVE-2021-22161?: In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates excessive network traffic between an affected device and its upstream ISP's router. This occurs when a link prefix route points to a point-to-point link, a destination IPv6 address belongs to the prefix and is not a local IPv6 address, and a router advertisement is received with at least one global unique IPv6 prefix for which the on-link flag is set. This affects the netifd and odhcp6c packages.
How severe is CVE-2021-22161?: CVE-2021-22161 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-22161 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-22161?: CVE-2021-22161 affects Openwrt. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-22161?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-22161 published?: CVE-2021-22161 was published on 2021-02-07 and last updated on 2026-06-17.

References

https://openwrt.org/advisory/2021-02-02-1

Affected products (1)

cpe:2.3:o:openwrt:openwrt:*:*:*:*:*:*:*:*

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