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CVE-2020-1656

Junos OS: When a DHCPv6 Relay-Agent is configured upon receipt of a specific DHCPv6 client message, Remote Code Execution may occur.

8.8 High

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.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.11%Down 1.7 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 8.8

Junos OS: When a DHCPv6 Relay-Agent is configured upon receipt of a specific DHCPv6 client message, Remote Code Execution may occur.

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.

Record
CVE-2020-1656
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-476, CWE-20
Updated
2026-11-02
EUVDEUVD-2020-12521 8.8

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.

Record
EUVD-2020-12521
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-g45c-9f6f-ww87 No score

The DHCPv6 Relay-Agent service, part of the Juniper Enhanced jdhcpd daemon shipped with Juniper...

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.

Record
GHSA-g45c-9f6f-ww87
Weakness
CWE-20
Updated
2026-11-02
NVD 8.8

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.

Record
CVE-2020-1656
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
5.8 MediumAV:A/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-20, CWE-476
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
facts
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-1656 is a high vulnerability (CVSS 8.8) in Juniper Junos, published October 16, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.11%, the 66th percentile. No source names a fixed version.

References

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