Junos OS: Uncontrolled Resource Consumption
CVE-2023-36841 is a high-severity uncontrolled resource consumption 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 20.4R3-S7, 21.1*, 21.2R3-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 0.62% chance of exploitation within 30 days, higher than 50% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Junos OS to 20.4R3-S7 or 21.1* or 21.2R3-S6 or 21.3R3-S5, whichever matches your release line, or a later version.
- Update Junos to 20.4 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 20.4R3-S7; 21.1R1 up to, but not including, 21.1*; 21.2 up to, but not including, 21.2R3-S6; 21.3 up to, but not including, 21.3R3-S5; 21.4 up to, but not including, 21.4R3-S3; 22.1 up to, but not including, 22.1R3-S4; 22.2 up to, but not including, 22.2R3; 22.3 up to, but not including, 22.3R2-S2, 22.3R3; and 11 more ranges | 20.4R3-S7, 21.1*, 21.2R3-S6, 21.3R3-S5, 21.4R3-S3, 22.1R3-S4 |
| Juniper Networks | Junos | before 20.4; 20.4; 21.1; 21.2; 21.3; 21.4; 22.1; 22.2; and 2 more ranges | 20.4 |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS). An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover. This issue affects interfaces with PPPoE configured and tcp-mss enabled. This issue affects Juniper Networks Junos OS * All versions prior to 20.4R3-S7; * 21.1 version 21.1R1 and later versions; * 21.2 versions prior to 21.2R3-S6; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S3; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3; * 22.3 versions prior to 22.3R2-S2; * 22.4 versions prior to 22.4R2;
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How developers prevent this class of flaw
- Ensure that protocols have specific limits of scale placed on them.
- Ensure that all failures in resource allocation place the system into a safe posture.
More Uncontrolled Resource Consumption vulnerabilities (CWE-400)
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 Uncontrolled Resource Consumption vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
HTTP/2 Rapid Reset Attack Exploited
- 7.5 High severity
- 7.5 High severity
- 8.6 High severity
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