Junos OS: Out-of-bounds Write
CVE-2024-39518 is a high-severity out-of-bounds write 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-S7, 21.4R3-S6, 22.2R3-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 0.42% 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-S7 or 21.4R3-S6 or 22.2R3-S4 or 22.3R3-S2, whichever matches your release line, 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 | 21.2R3-S5 up to, but not including, 21.2R3-S7; 21.4R3-S4 up to, but not including, 21.4R3-S6; 22.2R3 up to, but not including, 22.2R3-S4; 22.3R2 up to, but not including, 22.3R3-S2; 22.4R1 up to, but not including, 22.4R3; 23.2R1 up to, but not including, 23.2R2 | 21.2R3-S7, 21.4R3-S6, 22.2R3-S4, 22.3R3-S2, 22.4R3, 23.2R2 |
| Juniper Networks | Junos | 21.2; 21.4; 22.2; 22.3; 22.4; 23.2 | Not stated |
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 Heap-based Buffer Overflow vulnerability in the telemetry sensor process (sensord) of Juniper Networks Junos OS on MX240, MX480, MX960 platforms using MPC10E causes a steady increase in memory utilization, ultimately leading to a Denial of Service (DoS). When the device is subscribed to a specific subscription on Junos Telemetry Interface, a slow memory leak occurs and eventually all resources are consumed and the device becomes unresponsive. A manual reboot of the Line Card will be required to restore the device to its normal functioning. This issue is only seen when telemetry subscription is active. The Heap memory utilization can be monitored using the following command: > show system processes extensive The following command can be used to monitor the memory utilization of the specific sensor > show system info | match sensord PID NAME MEMORY PEAK MEMORY %CPU THREAD-COUNT CORE-AFFINITY UPTIME 1986 sensord 877.57MB 877.57MB 2 4 0,2-15 7-21:41:32 This issue affects Junos OS: * from 21.2R3-S5 before 21.2R3-S7, * from 21.4R3-S4 before 21.4R3-S6, * from 22.2R3 before 22.2R3-S4, * from 22.3R2 before 22.3R3-S2, * from 22.4R1 before 22.4R3, * from 23.2R1 before 23.2R2.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended 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.
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 Out-of-bounds Write vulnerabilities
- 7.0 High severity
- 8.2 High severity
- 8.2 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
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