VulnerabilityPublished 11 Jul 2025Updated 15 Jul 2025

CVE-2025-52951: Juniper Networks Junos OS · Protection Mechanism Failure

Affects Juniper Networks Junos OSSource CVE Database V5

Mentioned vulnerabilities

CVE-2024-21607

Not known to be exploited · CVSS 5.8 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

5.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Juniper Networks Junos OS	Affected 0 – 24.4 8 affected builds	Fixed in–

AI-suggested

To mitigate CVE-2025-52951, European organizations should take the following specific actions: 1) Immediately identify all Juniper Networks devices running affected versions of Junos OS, focusing on those with IPv6 enabled and firewall filters protecting the control plane. 2) Apply the latest security patches and updates from Juniper Networks that address this vulnerability. Since the advisory lists fixed versions starting from 21.2R3-S9 and subsequent releases, upgrading to these or later patched versions is critical. 3) Review and audit firewall filter configurations that use the 'payload-protocol' match criterion on control plane interfaces. Where possible, avoid using 'payload-protocol' in control plane filters until patched, or implement alternative filtering strategies that do not rely on this match. 4) Implement additional network segmentation and monitoring to detect anomalous IPv6 traffic targeting control plane interfaces. 5) Employ strict access control and management plane protection mechanisms such as management VRFs, ACLs, and control plane policing to limit exposure. 6) Monitor vendor advisories and threat intelligence feeds for any emerging exploits or indicators of compromise related to this vulnerability. 7) Conduct penetration testing and vulnerability assessments focusing on IPv6 control plane filtering to validate the effectiveness of mitigations.

Description

A Protection Mechanism Failure vulnerability in kernel filter processing of Juniper Networks Junos OS allows an attacker sending IPv6 traffic destined to the device to effectively bypass any firewall filtering configured on the interface. Due to an issue with Junos OS kernel filter processing, the 'payload-protocol' match is not being supported, causing any term containing it to accept all packets without taking any other action. In essence, these firewall filter terms were being processed as an 'accept' for all traffic on the interface destined for the control plane, even when used in combination with other match criteria. This issue only affects firewall filters protecting the device's control plane. Transit firewall filtering is unaffected by this vulnerability. This issue affects Junos OS: * all versions before 21.2R3-S9, * from 21.4 before 21.4R3-S11, * from 22.2 before 22.2R3-S7, * from 22.4 before 22.4R3-S7, * from 23.2 before 23.2R2-S4, * from 23.4 before 23.4R2-S5, * from 24.2 before 24.2R2-S1, * from 24.4 before 24.4R1-S2, 24.4R2. This is a more complete fix for previously published CVE-2024-21607 (JSA75748).

Impact

For European organizations, the impact of CVE-2025-52951 can be significant, especially for those relying on Juniper Networks Junos OS devices to secure their network infrastructure. The ability to bypass control plane firewall filters means attackers can potentially send malicious IPv6 traffic directly to the device's control plane, which could lead to unauthorized access to management interfaces, reconnaissance, or manipulation of control plane protocols. This undermines the security posture of critical network infrastructure, increasing the risk of further exploitation or lateral movement within the network. Since the vulnerability does not affect transit filtering, the risk is primarily to the device itself rather than traffic passing through it. However, compromised control plane security can lead to device misconfiguration, denial of management access, or indirect impacts on network stability. European organizations with IPv6-enabled networks and Junos OS devices in their core or edge infrastructure are particularly at risk. The medium severity rating suggests that while the vulnerability is exploitable remotely without authentication, the impact is limited to integrity and does not directly cause denial of service or data leakage. Nonetheless, the strategic importance of network infrastructure in sectors such as finance, telecommunications, government, and critical infrastructure in Europe elevates the potential consequences of exploitation.

CWE-693Protection Mechanism Failure (opens in a new tab)
Pillar weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Cross Site Tracing (opens in a new tab)
Directory Indexing (opens in a new tab)
Using Malicious Files (opens in a new tab)
Encryption Brute Forcing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

supportportal.juniper.net/JSA100055 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Jul 2025, 20:54 UTC

WeaknessesCWE-693

Technical details

References

Community reviews

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