Junos OS: Receipt of specific DHCPv6 packet may cause jdhcpd to crash and restart

published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2860

cvss: 7.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits: 0; none known

On Juniper Networks Junos OS platforms configured as DHCPv6 local server or DHCPv6 Relay Agent, Juniper Networks Dynamic Host Configuration Protocol Daemon (JDHCPD) process might crash with a core dump if a specific DHCPv6 packet is received, resulting in a restart of the daemon. The daemon automatically restarts without intervention, but continued receipt and processing of these specific packets will repeatedly crash the JDHCPD process and sustain the Denial of Service (DoS) condition. This issue only affects DHCPv6. DHCPv4 is not affected by this issue. This issue affects: Juniper Networks Junos OS 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1, 19.3R3-S2; 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R2, 20.1R3; 20.2 versions prior to 20.2R2, 20.2R3; 20.3 versions prior to 20.3R1-S2, 20.3R2.

Patch / fix

fixed in 1

Juniper Networks Junos OS 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R3-S7, 18.3R3-S4, 18.4R3-S7, 19.1R3-S4, 19.2R3-S1, 19.3R3-S1, 19.3R3-S2, 19.4R3-S1, 20.1R2, 20.1R3, 20.2R2, 20.2R3, 20.3R1-S2, 20.3R2

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.4	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD	3.1	6.5	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	3.3	AV:A/AC:L/Au:N/C:N/I:N/A:P

Affected products

Juniper Networks Junos OS

Classification

Weakness

CWE-703 Improper Check or Handling of Exceptional Conditions
CWE-755 Improper Handling of Exceptional Conditions

References

kb.juniper.net /JSA11168
vendor-advisory

Sources

CVE List CVE-2021-0241
NVD CVE-2021-0241

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary