Junos OS: Improper Handling of Exceptional Conditions
CVE-2024-39555 is a high-severity improper handling of exceptional conditions 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 21.4R3-S8, 22.2R3-S4, 22.3R3-S3 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 0.5% 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 21.4R3-S8 or 22.2R3-S4 or 22.3R3-S3 or 22.4R3-S3, whichever matches your release line, or a later version.
- Update Junos OS Evolved to 21.4R3-S8-EVO or 22.2R3-S4-EVO or 22.3R3-S3-EVO or 22.4R3-S3-EVO, whichever matches your release line, or a later version.
- Update Junos to 21.4 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 21.4R3-S8; 22.2 up to, but not including, 22.2R3-S4; 22.3 up to, but not including, 22.3R3-S3; 22.4 up to, but not including, 22.4R3-S3; 23.2 up to, but not including, 23.2R2-S1; 23.4 up to, but not including, 23.4R1-S2, 23.4R2; 23.4 up to, but not including, 23.4R1-S2; 23.4 up to, but not including, 23.4R2 | 21.4R3-S8, 22.2R3-S4, 22.3R3-S3, 22.4R3-S3, 23.2R2-S1, 23.4R1-S2, 23.4R2 |
| Juniper Networks | Junos OS Evolved | before 21.4R3-S8-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-S3-EVO; 23.2-EVO up to, but not including, 23.2R2-S1-EVO; 23.4-EVO up to, but not including, 23.4R1-S2-EVO, 23.4R2-EVO; 23.4-EVO up to, but not including, 23.4R1-S2-EVO; 23.4-EVO up to, but not including, 23.4R2-EVO | 21.4R3-S8-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S3-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO |
| Juniper Networks | Junos | before 21.4; 21.4; 22.2; 22.3; 22.4; 23.2; 23.4 | 21.4 |
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
An Improper Handling of Exceptional Conditions vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an attacker sending a specific malformed BGP update message to cause the session to reset, resulting in a Denial of Service (DoS). Continued receipt and processing of these malformed BGP update messages will create a sustained Denial of Service (DoS) condition. Upon receipt of a BGP update message over an established BGP session containing a specifically malformed tunnel encapsulation attribute, when segment routing is enabled, internal processing of the malformed attributes within the update results in improper parsing of remaining attributes, leading to session reset: BGP SEND Notification code 3 (Update Message Error) subcode 1 (invalid attribute list) Only systems with segment routing enabled are vulnerable to this issue. This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations, and requires a remote attacker to have at least one established BGP session. This issue affects: Junos OS: * All versions before 21.4R3-S8, * from 22.2 before 22.2R3-S4, * from 22.3 before 22.3R3-S3, * from 22.4 before 22.4R3-S3, * from 23.2 before 23.2R2-S1, * from 23.4 before 23.4R1-S2, 23.4R2. Junos OS Evolved: * All versions before 21.4R3-S8-EVO, * from 22.2-EVO before 22.2R3-S4-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S3-EVO, * from 23.2-EVO before 23.2R2-S1-EVO, * from 23.4-EVO before 23.4R1-S2-EVO, 23.4R2-EVO.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Exceptional Conditions
The product does not handle or incorrectly handles an exceptional condition.
More Improper Handling of Exceptional Conditions vulnerabilities (CWE-755)
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
- supportportal.juniper.net/JSA83015Mitigation
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 Handling of Exceptional Conditions vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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