Junos OS: Buffer Access with Incorrect Length Value
CVE-2025-30651 is a high-severity buffer access with incorrect length value vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 7.5 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 21.2R3-S9, 21.4R3-S10, 22.2R3-S6 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 0.43% 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 21.2R3-S9 or 21.4R3-S10 or 22.2R3-S6 or 22.4R3-S4, whichever matches your release line, or a later version.
- Update Junos OS Evolved to 21.2R3-S9-EVO or 21.4R3-S10-EVO or 22.2R3-S6-EVO or 22.4R3-S4-EVO, whichever matches your release line, or a later version.
- Update Junos to 21.2 or a later version.
- Read the advisory on supportportal.juniper.net for workarounds and exact fixed builds.
- 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 21.2R3-S9; 21.4 up to, but not including, 21.4R3-S10; 22.2 up to, but not including, 22.2R3-S6; 22.4 up to, but not including, 22.4R3-S4; 23.2 up to, but not including, 23.2R2-S2; 23.4 up to, but not including, 23.4R2 | 21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S4, 23.2R2-S2, 23.4R2 |
| Juniper Networks | Junos OS Evolved | before 21.2R3-S9-EVO; 21.4-EVO up to, but not including, 21.4R3-S10-EVO; 22.2-EVO up to, but not including, 22.2R3-S6-EVO; 22.4-EVO up to, but not including, 22.4R3-S4-EVO; 23.2-EVO up to, but not including, 23.2R2-S2-EVO; 23.4-EVO up to, but not including, 23.4R2-EVO | 21.2R3-S9-EVO, 21.4R3-S10-EVO, 22.2R3-S6-EVO, 22.4R3-S4-EVO, 23.2R2-S2-EVO, 23.4R2-EVO |
| Juniper Networks | Junos | before 21.2; 21.2; 21.4; 22.2; 22.4; 23.2; 23.4 | 21.2 |
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
- LowNo special conditions are needed; the attack works reliably.
- 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
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.5 | High | CNA (juniper.net) |
Official description
A Buffer Access with Incorrect Length Value vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS). When an attacker sends a specific ICMPv6 packet to an interface with "protocols router-advertisement" configured, rpd crashes and restarts. Continued receipt of this packet will cause a sustained DoS condition. This issue only affects systems configured with IPv6. This issue affects Junos OS: * All versions before 21.2R3-S9, * from 21.4 before 21.4R3-S10, * from 22.2 before 22.2R3-S6, * from 22.4 before 22.4R3-S4, * from 23.2 before 23.2R2-S2, * from 23.4 before 23.4R2; and Junos OS Evolved: * All versions before 21.2R3-S9-EVO, * from 21.4-EVO before 21.4R3-S10-EVO, * from 22.2-EVO before 22.2R3-S6-EVO, * from 22.4-EVO before 22.4R3-S4-EVO, * from 23.2-EVO before 23.2R2-S2-EVO, * from 23.4-EVO before 23.4R2-EVO.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Buffer Access with Incorrect Length Value
The product uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
More Buffer Access with Incorrect Length Value vulnerabilities (CWE-805)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
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 Buffer Access with Incorrect Length Value vulnerabilities
- 7.4 High severity
- 7.7 High severity
- 7.7 High severity
- 7.7 High severity
- 7.7 High severity
- 7.4 High severity
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