CVE-2021-31353
An Improper Handling of Exceptional Conditions vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows an attacker to inject a specific BGP update, causing the routing protocol daemon (RPD) to crash and restart, leading to a Denial of Service (DoS). Continued receipt and processing of the BGP update will create a sustained Denial of Service (DoS) condition. This issue affects very specific versions of Juniper Networks Junos OS: 19.3R3-S2; 19.4R3-S3; 20.2 versions 20.2R2-S3 and later, prior to 20.2R3-S2; 20.3 versions 20.3R2 and later, prior to 20.3R3; 20.4 versions 20.4R2 and later, prior to 20.4R3; 21.1 versions prior to 21.1R2. Juniper Networks Junos OS 20.1 is not affected by this issue. This issue also affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R2-S3-EVO, 20.4R3-EVO; 21.1-EVO versions prior to 21.1R2-EVO; 21.2-EVO versions prior to 21.2R2-EVO.
- Affected products
- Junos, Junos Evolved
- Juniper Junos
- = 19.3, 19.4, 20.2, 20.3, 20.4, 21.1
- Juniper Junos Os Evolved
- ≤ 20.3, 20.4, 21.1, 21.2
- Fix
- Available
- CVSS 3.1
- 7.5 HIGH
- EPSS
- 1.1% (63th percentile)
- Weakness
- CWE-755
- NVD status
- Modified
- Published
- 2021-10-19
Fix
The following software releases have been updated to resolve this specific issue: Junos OS 18.4R2-S9, 19.1R3-S7, 19.3R3-S3, 19.4R1-S4, 19.4R3-S4, 20.1R3, 20.2R3-S2, 20.3R3, 20.4R3, 21.1R2, 21.2R1, 21.2R2, 21.3R1, and all subsequent releases. Junos OS Evolved 20.4R2-S3-EVO, 20.4R3-EVO, 21.1R2-EVO, 21.2R2-EVO, 21.3R1-EVO, and all subsequent releases. Note: Only those releases listed in the PROBLEM section above are affected. This fix has also been proactively committed into other releases that are not vulnerable to this issue.
Workaround
This issue can be mitigated in two ways: 1) ensure that TTL propagation is either enabled or disabled in both places below: protocols mpls no-propagate-ttl routing-instance no-vrf-propagate-ttl 2) Disable multipath: routing-instance routing-options multipath
No indexed exploits for CVE-2021-31353 yet
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No exploit for CVE-2021-31353 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.