Race condition in Juniper Junos OS
Priority LOW 34CWE-362Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-416 and the CVSS impact.
Summary
On PTX Series and QFX10k Series devices with the "inline-jflow" feature enabled, a use after free weakness in the Packet Forwarding Engine (PFE) microkernel architecture of Juniper Networks Junos OS may allow an attacker to cause a Denial of Service (DoS) condition whereby one or more Flexible PIC Concentrators (FPCs) may restart. As this is a race condition situation this issue become more likely to be hit when network instability occurs, such as but not limited to BGP/IGP reconvergences, and/or further likely to occur when more active "traffic flows" are occurring through the device. When this issue occurs, it will cause one or more FPCs to restart unexpectedly. During FPC restarts core files will be generated. While the core file is generated traffic will be disrupted. Sustained receipt of large traffic flows and reconvergence-like situations may sustain the Denial of Service (DoS) situation. This issue affects: Juniper Networks Junos OS: 18.1 version 18.1R2 and later versions prior to 18.1R3-S10 on PTX Series, QFX10K Series.
Why it matters now
EPSS 0.00722 54th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Juniper | Junos OS | 18.1R2 and later | — | No fix listed | CNA |
- Junos OS VendorJuniper Affected 18.1R2 and later Fixed in — No fix listed CNA
CPE configurations NVD · 26
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:juniper:junos:18.1:r2:*:*:*:*:*:* | 18.1 r2 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r2-s1:*:*:*:*:*:* | 18.1 r2-s1 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r2-s2:*:*:*:*:*:* | 18.1 r2-s2 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r2-s4:*:*:*:*:*:* | 18.1 r2-s4 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3:*:*:*:*:*:* | 18.1 r3 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s1:*:*:*:*:*:* | 18.1 r3-s1 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s2:*:*:*:*:*:* | 18.1 r3-s2 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s3:*:*:*:*:*:* | 18.1 r3-s3 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s4:*:*:*:*:*:* | 18.1 r3-s4 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s5:*:*:*:*:*:* | 18.1 r3-s5 | Vulnerable | Juniper |
- cpe:2.3:o:juniper:junos:18.1:r2:*:*:*:*:*:* Versions 18.1 r2 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r2-s1:*:*:*:*:*:* Versions 18.1 r2-s1 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r2-s2:*:*:*:*:*:* Versions 18.1 r2-s2 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r2-s4:*:*:*:*:*:* Versions 18.1 r2-s4 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3:*:*:*:*:*:* Versions 18.1 r3 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s1:*:*:*:*:*:* Versions 18.1 r3-s1 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s2:*:*:*:*:*:* Versions 18.1 r3-s2 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s3:*:*:*:*:*:* Versions 18.1 r3-s3 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s4:*:*:*:*:*:* Versions 18.1 r3-s4 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s5:*:*:*:*:*:* Versions 18.1 r3-s5 Vulnerable ·Juniper
Show 16 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:juniper:junos:18.1:r3-s6:*:*:*:*:*:* | 18.1 r3-s6 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s7:*:*:*:*:*:* | 18.1 r3-s7 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s8:*:*:*:*:*:* | 18.1 r3-s8 | Vulnerable | Juniper |
| cpe:2.3:o:juniper:junos:18.1:r3-s9:*:*:*:*:*:* | 18.1 r3-s9 | Vulnerable | Juniper |
| cpe:2.3:h:juniper:ptx1000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10001-36mr:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10002:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10003:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10004:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10008:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx10016:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx3000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:ptx5000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:qfx10002:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:qfx10008:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
| cpe:2.3:h:juniper:qfx10016:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Juniper |
- cpe:2.3:o:juniper:junos:18.1:r3-s6:*:*:*:*:*:* Versions 18.1 r3-s6 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s7:*:*:*:*:*:* Versions 18.1 r3-s7 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s8:*:*:*:*:*:* Versions 18.1 r3-s8 Vulnerable ·Juniper
- cpe:2.3:o:juniper:junos:18.1:r3-s9:*:*:*:*:*:* Versions 18.1 r3-s9 Vulnerable ·Juniper
- cpe:2.3:h:juniper:ptx1000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10001-36mr:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10002:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10003:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10004:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10008:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx10016:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx3000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:ptx5000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:qfx10002:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:qfx10008:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
- cpe:2.3:h:juniper:qfx10016:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Juniper
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-0270
- 2026-10-03 Alias added: GHSA-4633-w3xc-3953
References
More Juniper Junos vulnerabilities
- TI-2023-18638 Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to… KEVCVSS 3.1CRITICAL 9.8
- TI-2020-01585 Out of Cycle Security Advisory: Junos OS: Security vulnerability in J-Web and web based (HTTP/HTTPS) services KEVCVSS 3.1CRITICAL 9.8
- TI-2015-04610 Assertion failure in ISC BIND named via TKEY queries KEVCVSS 3.1HIGH 7.5
- TI-2025-15550 Junos OS: An local attacker with shell access can execute arbitrary code KEVCVSS 4.0MEDIUM 6.7
- TI-2023-18644 Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload and download arbitrary files KEVCVSS 3.1MEDIUM 5.3
- TI-2023-18640 Junos OS: EX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary files KEVCVSS 3.1MEDIUM 5.3
Sources
- CVE-2021-0270 · CVE Program
- CVE-2021-0270 · NVD
- FIRST EPSS
- GHSA-4633-w3xc-3953 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences