Junos OS: Improper Validation of Syntactic Correctness of Input
CVE-2026-102084 is a high-severity improper validation of syntactic correctness of input vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 23.2R2-S7.7, 23.4R2-S7, 24.2R2-S4 as the first without the flaw, so updating Junos OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.51% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Junos OS to 23.2R2-S7.7 or 23.4R2-S7 or 24.2R2-S4 or 24.4R2-S3, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS | before 23.2R2-S7.7; 23.4 up to, but not including, 23.4R2-S7; 24.2 up to, but not including, 24.2R2-S4; 24.4 up to, but not including, 24.4R2-S3; 25.2 up to, but not including, 25.2R2; 25.4 up to, but not including, 25.4R1-S3 | 23.2R2-S7.7, 23.4R2-S7, 24.2R2-S4, 24.4R2-S3, 25.2R2, 25.4R1-S3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.2 | Critical | CNA (juniper.net) |
| CVSS 3.1 | 8.1 | High | CNA (juniper.net) |
Official description
An Improper Validation of Syntactic Correctness of Input vulnerability in the VPN daemon of Juniper Networks Junos OS on SRX Series allows an authenticated, network-based attacker to take complete control of the device. If an SRX device configured for AutoDiscovery VPN (ADVPN) receives a message from a peer that contains one or more specifically malformed attributes, this will cause a buffer overflow, which can allow remote code execution and therefore allow an attacker to take complete control of the device. To be able to carry out this attack an attacker must either have acquired the shared secret to impersonate a peer or have compromised an existing one, so this attack is considerably difficult. This issue affects Junos OS on SRX Series: * All versions before 23.2R2-S7.7; * from 23.4 before 23.4R2-S7; * from 24.2 before 24.2R2-S4; * from 24.4 before 24.4R2-S3; * from 25.2 before 25.2R2; * from 25.4 before 25.4R1-S3.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Syntactic Correctness of Input
The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.
More Improper Validation of Syntactic Correctness of Input vulnerabilities (CWE-1286)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Junos OS
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
Recent Improper Validation of Syntactic Correctness of Input vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.1 High severity
- 8.3 High severity
- 7.5 High severity
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