CVE-2025-21600

An Out-of-Bounds Read vulnerability in

the routing protocol daemon (rpd) of

Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, logically adjacent BGP peer sending a specifically malformed BGP packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition.

This issue only affects systems configured in either of two ways:

    *  systems with BGP traceoptions enabled

    *  systems with BGP family traffic-engineering (BGP-LS)
      configured

and can be exploited from a directly connected and configured BGP peer. 

This issue affects iBGP and eBGP

with

any address family

configured, and both IPv4 and IPv6 are affected by this vulnerability.

This issue affects:

Junos OS: 

from 21.4 before 21.4R3-S9, 

• from 22.2 before 22.2R3-S5, 
• from 22.3 before 22.3R3-S4, 
• from 22.4 before 22.4R3-S5, 
• from 23.2 before 23.2R2-S3, 
• from 23.4 before 23.4R2-S3, 
• from 24.2 before 24.2R1-S2, 24.2R2; 

Junos OS Evolved: 

• from 21.4-EVO before 21.4R3-S9-EVO, 
• from 22.2-EVO before 22.2R3-S5-EVO, 
• from 22.3-EVO before 22.3R3-S4-EVO, 
• from 22.4-EVO before 22.4R3-S5-EVO, 
• from 23.2-EVO before 23.2R2-S3-EVO, 
• from 23.4-EVO before 23.4R2-S2-EVO, 
• from 24.2-EVO before 24.2R1-S2-EVO, 24.2R2-EVO.

This issue does not affect versions of Junos OS prior to 21.3R1.

This issue does not affect versions of Junos OS Evolved prior to 21.3R1-EVO.

This is a similar, but different vulnerability than the issue reported as CVE-2024-39516.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://supportportal.juniper.net/JSA92870