Junos OS Evolved: Missing Authentication for Critical Functionality
CVE-2026-33788 is a high-severity missing authentication for critical functionality vulnerability in Junos OS Evolved from Juniper Networks, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.2R3-S4-EVO as the first without the flaw, so updating Junos OS Evolved to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.12% 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 Evolved to 21.2R3-S8-EVO or 21.4R3-S7-EVO or 22.2R3-S4-EVO or 22.3R3-S3-EVO, whichever matches your release line, or a later version.
- Read the advisory on kb.juniper.net for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS Evolved | before 21.2R3-S8-EVO; 21.4-EVO up to, but not including, 21.4R3-S7-EVO; 22.2-EVO up to, but not including, 22.2R3-S4-EVO; 22.3-EVO up to, but not including, 22.3R3-S3-EVO; 22.4-EVO up to, but not including, 22.4R3-S2-EVO; 23.2-EVO up to, but not including, 23.2R2-EVO | 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S2-EVO, 23.2R2-EVO |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.5 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.8 | High | CNA (juniper.net) |
Official description
A Missing Authentication for Critical Function vulnerability in the Flexible PIC Concentrators (FPCs) of Juniper Networks Junos OS Evolved on PTX Series allows a local, authenticated attacker with low privileges to gain direct access to FPCs installed in the device. A local user with low privileges can gain direct access to the installed FPCs as a high privileged user, which can potentially lead to a full compromise of the affected component. This issue affects Junos OS Evolved on PTX10004, PTX10008, PTX100016, with JNP10K-LC1201 or JNP10K-LC1202: * All versions before 21.2R3-S8-EVO, * 21.4-EVO versions before 21.4R3-S7-EVO, * 22.2-EVO versions before 22.2R3-S4-EVO, * 22.3-EVO versions before 22.3R3-S3-EVO, * 22.4-EVO versions before 22.4R3-S2-EVO, * 23.2-EVO versions before 23.2R2-EVO.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authentication for Critical Functionality
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
- When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.
More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)
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
Advisories
Other vulnerabilities in Junos OS Evolved
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
Recent Missing Authentication for Critical Functionality vulnerabilities
- 8.6 High severity
- 9.8 Critical severity
Marimo Remote Code Execution Exploited
- 8.1 High severity
- 9.1 Critical severity
- 7.5 High severity
- 9.8 Critical severity
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