By flooding a Juniper Networks router running Junos OS with specially crafted IPv6 traffic, all available resources can be consumed, leading to the inability to store next hop information for legitimate traffic. In extreme cases, the crafted IPv6 traffic may result in a total resource exhaustion and kernel panic. The issue is triggered by traffic destined to the router. Transit traffic does not trigger the vulnerability. This issue only affects devices with IPv6 enabled and configured. Devices not configured to process IPv6 traffic are unaffected by this vulnerability. This issue was found during internal product security testing. Juniper SIRT is not aware of any malicious exploitation of this vulnerability. Affected releases are Juniper Networks Junos OS 11.4 prior to 11.4R13-S3; 12.3 prior to 12.3R3-S4; 12.3X48 prior to 12.3X48-D30; 13.3 prior to 13.3R10, 13.3R4-S11; 14.1 prior to 14.1R2-S8, 14.1R4-S12, 14.1R8; 14.1X53 prior to 14.1X53-D28, 14.1X53-D40; 14.1X55 prior to 14.1X55-D35; 14.2 prior to 14.2R3-S10, 14.2R4-S7, 14.2R6; 15.1 prior to 15.1F2-S5, 15.1F5-S2, 15.1F6, 15.1R3; 15.1X49 prior to 15.1X49-D40; 15.1X53 prior to 15.1X53-D57, 15.1X53-D70.
CVE-2016-4921
HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence
Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2022-05-13. NVD baseline CVSS 7.5; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 7.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 85.3%
- KEV
- Not listed
Published
October 13, 2017
Last Modified
May 13, 2026
References (6)
- sirt@juniperhttp://www.securityfocus.com/bid/93532
- sirt@juniperhttp://www.securitytracker.com/id/1037014
- sirt@juniperhttps://kb.juniper.net/JSA10762
- af854a3a-2127-422b-91ae-364da2661108http://www.securityfocus.com/bid/93532
- af854a3a-2127-422b-91ae-364da2661108http://www.securitytracker.com/id/1037014
- af854a3a-2127-422b-91ae-364da2661108https://kb.juniper.net/JSA10762
Data Freshness Timeline
(refreshed 9× in last 7d / 42× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-07 13:42 UTCEPSS rescore
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- 2026-05-22 08:59 UTCGHSA enrichment
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Frequently asked(5)
What is CVE-2016-4921?
CVE-2016-4921 is a high vulnerability published on October 13, 2017. By flooding a Juniper Networks router running Junos OS with specially crafted IPv6 traffic, all available resources can be consumed, leading to the inability to store next hop information for legitimate traffic. In extreme cases, the crafted IPv6 traffic may result in a total resource exhaustion…
When was CVE-2016-4921 disclosed?
CVE-2016-4921 was first published in the National Vulnerability Database on October 13, 2017, with the most recent update on May 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-4921 actively exploited?
CVE-2016-4921 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 85.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-4921?
CVE-2016-4921 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2016-4921?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-4921, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2016-4921
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