CVE-2025-21597 | Junos OS and Junos OS Evolved: When BGP rib-sharding and update-threading are configured and a peer flaps, an rpd core is observed

An Improper Check for Unusual or Exceptional Conditions vulnerability in routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, logically adjacent BGP peer to cause Denial of Service (DoS). On all Junos OS and Junos OS Evolved platforms, when BGP rib-sharding and update-threading are configured, and a BGP peer flap is done with specific timing, rpd crashes and restarts. Continuous peer flapping at specific time intervals will result in a sustained Denial of Service (DoS) condition. This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. The issue can occur with or without logical-systems enabled. This issue affects: Junos OS: * All versions before 20.4R3-S8, * 21.2 versions before 21.2R3-S6, * 21.3 versions before 21.3R3-S5, * 21.4 versions before 21.4R3-S4, * 22.1 versions before 22.1R3-S3, * 22.2 versions before 22.2R3-S1, * 22.3 versions before 22.3R3, * 22.4 versions before 22.4R3. Junos OS Evolved: * All versions before 21.2R3-S6-EVO, * 21.3-EVO versions before 21.3R3-S5-EVO, * 21.4-EVO versions before 21.4R3-S4-EVO, * 22.1-EVO versions before 22.1R3-S3-EVO, * 22.2-EVO versions before :22.2R3-S1-EVO, * 22.3-EVO versions before 22.3R3-EVO, * 22.4-EVO versions before 22.4R3-EVO.

Published: 2025-04-09 Last update: 2026-01-26 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-21597 is rated Moderate Risk (51.1/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.92%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-21597

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-24 0.55% 0.92% +0.37%
2 2026-05-22 0.64% 0.55% -0.09%
3 2026-05-18 — 0.64% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21597

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.0 4.0 MEDIUM
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:A/V:X/RE:X/U:X Click to expand
Attack vector (AV:A)
Attacker has to be on an adjacent/local network segment.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:L)
Limited availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:A)
Automatic: services recover on their own after an attack.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.6 3.6 [email protected]

Weakness enumeration for CVE-2025-21597

Affected software / configurations for CVE-2025-21597

Vendor Product Version Raw CPE
juniper junos < 20.4 cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:-:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r1:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r1-s1:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r2:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r2-s1:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r2-s2:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s1:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s2:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s3:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s4:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s5:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s6:*:*:*:*:*:*
juniper junos 20.4 cpe:2.3:o:juniper:junos:20.4:r3-s7:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:-:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r1:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r1-s1:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r1-s2:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r2:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r2-s1:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r2-s2:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3-s1:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3-s2:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3-s3:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3-s4:*:*:*:*:*:*
juniper junos 21.2 cpe:2.3:o:juniper:junos:21.2:r3-s5:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:-:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r1:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r1-s1:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r1-s2:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r2:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r2-s1:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r2-s2:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r3:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r3-s1:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r3-s2:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r3-s3:*:*:*:*:*:*
juniper junos 21.3 cpe:2.3:o:juniper:junos:21.3:r3-s4:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:-:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s3:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:-:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r1:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r1-s1:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r1-s2:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r2:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r2-s1:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r2-s2:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r3:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r3-s1:*:*:*:*:*:*
juniper junos 22.1 cpe:2.3:o:juniper:junos:22.1:r3-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:-:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1-s1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2-s1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:-:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r1:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r1-s1:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r1-s2:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r2:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r2-s1:*:*:*:*:*:*
juniper junos 22.3 cpe:2.3:o:juniper:junos:22.3:r2-s2:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*

References for CVE-2025-21597

URL Tags
https://kb.juniper.net/JSA96451 Vendor Advisory
cvelogic Threat Intelligence