CyberSecBulletin
CVE-2023-4481NVD status: Modified

An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper…

Published Updated By the CyberSecBulletin desk

CVE-2023-4481 is a high-severity improper input validation 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-S10, 21.2R3-S5, 21.3R3-S5 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 18.4% chance of exploitation within 30 days, which is in the top 2.72% of all scored CVEs.

Patch this week

EPSS places it among the vulnerabilities most likely to be exploited soon.

What to do

  1. Update Junos OS to 20.4R3-S10 or 21.2R3-S5 or 21.3R3-S5 or 21.4R3-S7, whichever matches your release line, or a later version.
  2. Update Junos OS Evolved to 20.4R3-S10-EVO or 21.2R3-S7-EVO or 21.3R3-S5-EVO or 21.4R3-S5-EVO, whichever matches your release line, or a later version.
  3. Update Junos to 20.4 or a later version.
  4. Read the advisory on kb.juniper.net for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Juniper NetworksJunos OSbefore 20.4R3-S10; 21.2 up to, but not including, 21.2R3-S5; 21.3 up to, but not including, 21.3R3-S5; 21.4 up to, but not including, 21.4R3-S7; 22.1 up to, but not including, 22.1R3-S4; 22.2 up to, but not including, 22.2R3-S3; 22.3 up to, but not including, 22.3R3-S1; 22.4 up to, but not including, 22.4R3; and 3 more ranges20.4R3-S10, 21.2R3-S5, 21.3R3-S5, 21.4R3-S7, 22.1R3-S4, 22.2R3-S3
Juniper NetworksJunos OS Evolvedbefore 20.4R3-S10-EVO; 21.2-EVO up to, but not including, 21.2R3-S7-EVO; 21.3-EVO up to, but not including, 21.3R3-S5-EVO; 21.4-EVO up to, but not including, 21.4R3-S5-EVO; 22.1-EVO up to, but not including, 22.1R3-S4-EVO; 22.2-EVO up to, but not including, 22.2R3-S3-EVO; 22.3-EVO up to, but not including, 22.3R3-S1-EVO; 22.4-EVO up to, but not including, 22.4R3-EVO; and 1 more ranges20.4R3-S10-EVO, 21.2R3-S7-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S3-EVO
Juniper NetworksJunosbefore 20.4; 20.4; 21.1; 21.2; 21.3; 21.4; 22.1; 22.2; and 3 more ranges20.4

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).

Official description

An Improper Input Validation 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 certain specific crafted BGP UPDATE messages are received over an established BGP session, one BGP session may be torn down with an UPDATE message error, or the issue may propagate beyond the local system which will remain non-impacted, but may affect one or more remote systems. This issue is exploitable remotely as the crafted UPDATE message can propagate through unaffected systems and intermediate BGP speakers. Continuous receipt of the crafted BGP UPDATE messages will create a sustained Denial of Service (DoS) condition for impacted devices. This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. Improper Input Validation, Denial of Service vulnerability in Juniper Networks, Inc. Junos OS (BGP, rpd modules), Juniper Networks, Inc. Junos OS Evolved (BGP, rpd modules) allows Fuzzing.This issue affects Junos OS: * All versions before 20.4R3-S10, * from 21.1R1 through 21.*, * from 21.2 before 21.2R3-S5, * from 21.3 before 21.3R3-S5, * from 21.4 before 21.4R3-S7 (unaffected from 21.4R3-S5, affected from 21.4R3-S6) * from 22.1 before 22.1R3-S4, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3-S1, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2. Junos OS Evolved: * All versions before 20.4R3-S10-EVO, * from 21.2-EVO before 21.2R3-S7-EVO, * from 21.3-EVO before 21.3R3-S5-EVO, * from 21.4-EVO before 21.4R3-S5-EVO, * from 22.1-EVO before 22.1R3-S4-EVO, * from 22.2-EVO before 22.2R3-S3-EVO, * from 22.3-EVO before 22.3R3-S1-EVO, * from 22.4-EVO before 22.4R3-EVO, * from 23.2-EVO before 23.2R2-EVO.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other references

Other vulnerabilities in Junos OS

All Junos OS vulnerabilities

Recent Improper Input Validation vulnerabilities

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