Cisco StarOS IPv6 Denial of Service Vulnerability
Noroxi assessment
Priority: Monitor (action score 34/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 1.6% (FIRST EPSS); higher than 75.8% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to the record, no fixed version is available yet.
Low priority for now. Update when a fix is released; follow the vendor's advisory.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
A vulnerability in the IPv6 implementation of Cisco StarOS could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient validation of incoming IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet to an affected device with the goal of reaching the vulnerable section of the input buffer. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. This vulnerability is specific to IPv6 traffic. IPv4 traffic is not affected.
- Published
- Aug 17, 2020
- Updated
- Jun 16, 2026
- EPSS
- 1.6% · 75th percentile
- CWE
- CWE-119
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.6%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 8.6
- CNA · cisco
- 6.8
- 1.8 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- No fixed version yet
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| cisco | staros | cpe:2.3:o:cisco:staros |
| cisco | virtualized packet core-single instance | cpe:2.3:a:cisco:virtualized_packet_core-single_instance |
| cisco | asr 5500 | cpe:2.3:h:cisco:asr_5500 |
| cisco | asr 5700 | cpe:2.3:h:cisco:asr_5700 |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco starosbefore 21.18.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.
Cisco Cisco ASR 5000 Series Software
- n/aaffected
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-20046A vulnerability in the key-based SSH authentication feature of Cisco StarOS Software could allow an authenticated, remote attacker to elevat35Monitor
- CVE-2021-1539Cisco ASR 5000 Series Software Authorization Bypass Vulnerabilities35Monitor
- CVE-2018-0369A vulnerability in the reassembly logic for fragmented IPv4 packets of Cisco StarOS running on virtual platforms could allow an unauthentica35Monitor
Published before and after this one in the same product
- ← EarlierCVE-2019-16026Jan 26, 2020 · Cisco Mobility Management Entity Denial of Service Vulnerability23Monitor
- ← EarlierCVE-2020-3244Jun 17, 2020 · Cisco ASR 5000 Series Aggregation Services Routers Enhanced Charging Service Rule Bypass Vulnerability21Monitor
- Later →CVE-2020-3601Oct 8, 2020 · Cisco StarOS Privilege Escalation Vulnerability26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory BufferCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Buffer ManipulationCAPEC-123likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
—
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.