How severe is CVE-2016-6421?

CVE-2016-6421 has a CVSS 3.x base score of 5.3, rated medium 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 low.

Is CVE-2016-6421 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6421?

CVE-2016-6421 affects Cisco Ios Xr. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-6421?

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

When was CVE-2016-6421 published?

CVE-2016-6421 was published on 2016-10-05 and last updated on 2026-06-17.

CVE-2016-6421

CVE-2016-6421 is a medium-severity vulnerability in Cisco Ios Xr with a CVSS 3.x base score of 5.3. 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-399.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Cisco Ios Xr
Published: 2016-10-05
Last modified: 2026-06-17

Description

Cisco IOS XR 5.2.2 allows remote attackers to cause a denial of service (process restart) via a crafted OSPF Link State Advertisement (LSA) update, aka Bug ID CSCvb05643.

Frequently asked questions

What is CVE-2016-6421?: Cisco IOS XR 5.2.2 allows remote attackers to cause a denial of service (process restart) via a crafted OSPF Link State Advertisement (LSA) update, aka Bug ID CSCvb05643.
How severe is CVE-2016-6421?: CVE-2016-6421 has a CVSS 3.x base score of 5.3, rated medium 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 low.
Is CVE-2016-6421 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6421?: CVE-2016-6421 affects Cisco Ios Xr. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-6421?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-6421 published?: CVE-2016-6421 was published on 2016-10-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:cisco:ios_xr:5.2.2:*:*:*:*:*:*:*

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