CVE-2020-1656
No exploitation reported by the sources we read.
- Published2020-10-16
- WeaknessCWE-20 · CWE-476
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
The DHCPv6 Relay-Agent service, part of the Juniper Enhanced jdhcpd daemon shipped with Juniper Networks Junos OS has an Improper Input Validation vulnerability which will result in a Denial of Service (DoS) condition when a DHCPv6 client sends a specific DHPCv6 message allowing an attacker to potentially perform a Remote Code Execution (RCE) attack on the target device. Continuous receipt of the specific DHCPv6 client message will result in an extended Denial of Service (DoS) condition. If adjacent devices are also configured to relay DHCP packets, and are not affected by this issue and simply transparently forward unprocessed client DHCPv6 messages, then the attack vector can be a Network-based attack, instead of an Adjacent-device attack. No other DHCP services are affected. Receipt of the packet without configuration of the DHCPv6 Relay-Agent service, will not result in exploitability of this issue. This issue affects Juniper Networks Junos OS: 12.3 versions prior to 12.3R12-S15; 12.3X48 versions prior to 12.3X48-D95; 14.1X53 versions prior to 14.1X53-D53; 15.1 versions prior to 15.1R7-S6; 15.1X49 versions prior to 15.1X49-D200; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S7; 16.2 versions prior to 16.2R2-S11; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2; 17.2 versions prior to 17.2R3-S3; 17.2X75 versions prior to 17.2X75-D44; 17.3 versions prior to 17.3R3-S7; 17.4 versions prior to 17.4R2-S9, 17.4R3; 18.1 versions prior to 18.1R3-S9; 18.2 versions prior to 18.2R2-S6, 18.2R3-S2; 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D33, 18.2X75-D435, 18.2X75-D60; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3-S1; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3; 19.1 versions prior to 19.1R1-S4, 19.1R2; 19.2 versions prior to 19.2R1-S3, 19.2R2; 19.3 versions prior to 19.3R2.
Timeline
dates in UTC- 2020-10-1621:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-1656?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-1656?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 12.3 | = 12.3 | no fix published | NVD |
| 12.3 | = 12.3x48 | no fix published | NVD |
| 14.1 | = 14.1x53 | no fix published | NVD |
| 15.1 | = 15.1 | no fix published | NVD |
| 15.1 | = 15.1x49 | no fix published | NVD |
| 15.1 | = 15.1x53 | no fix published | NVD |
| 16.1 | = 16.1 | no fix published | NVD |
| 16.2 | = 16.2 | no fix published | NVD |
| 17.1 | = 17.1 | no fix published | NVD |
| 17.2 | = 17.2 | no fix published | NVD |
| 17.2 | = 17.2x75 | no fix published | NVD |
| 17.3 | = 17.3 | no fix published | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
Advisories and patches
- kb.juniper.netVendor Advisory
- www.juniper.netVendor Advisory
- www.juniper.netVendor Advisory
- www.juniper.netVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- CNACVSS 3.18.8read 2026-10-23
- NVDCVSS 2.05.8read 2026-10-23
- CNAweakness (CWE)CWE-20, CWE-476read 2026-10-23
- NVDweakness (CWE)CWE-20read 2026-10-23
- FIRST EPSSEPSS score1.1 %2026-10-23
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Published
- 2020-10-16
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
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