# CVE-2020-1653: Junos OS: Kernel crash (vmcore) or FPC crash due to mbuf leak > Remote attackers can cause a denial of service on Juniper Junos OS devices by sending TCP packets that trigger an mbuf leak, leading to system crashes. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 17 Jul 2020 - **Updated:** 17 Sep 2024 - **Also known as:** GHSA-q694-5rvh-m24r ## What is CVE-2020-1653? CVE-2020-1653 is a high-severity denial of service vulnerability in Juniper Junos, published on 17 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description On Juniper Networks Junos OS devices, a stream of TCP packets sent to the Routing Engine (RE) may cause mbuf leak which can lead to Flexible PIC Concentrator (FPC) crash or the system to crash and restart (vmcore). This issue can be trigged by IPv4 or IPv6 and it is caused only by TCP packets. This issue is not related to any specific configuration and it affects Junos OS releases starting from 17.4R1. However, this issue does not affect Junos OS releases prior to 18.2R1 when Nonstop active routing (NSR) is configured [edit routing-options nonstop-routing]. The number of mbufs is platform dependent. The following command provides the number of mbufs counter that are currently in use and maximum number of mbufs that can be allocated on a platform: user@host> show system buffers 2437/3143/5580 mbufs in use (current/cache/total) Once the device runs out of mbufs, the FPC crashes or the vmcore occurs and the device might become inaccessible requiring a manual restart. This issue affects Juniper Networks Junos OS 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S5; 18.2X75 versions prior to 18.2X75-D41, 18.2X75-D420.12, 18.2X75-D51, 18.2X75-D60, 18.2X75-D34; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3-S1; 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S3, 19.3R3; 19.4 versions prior to 19.4R1-S2, 19.4R2. Versions of Junos OS prior to 17.4R1 are unaffected by this vulnerability. Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime), CWE-159 (Improper Handling of Invalid Use of Special Elements) ## Which versions are affected by CVE-2020-1653? It affects 1 product. Products: Juniper Junos. ## How do I fix CVE-2020-1653? No fix has been published for CVE-2020-1653 yet. Limit exposure of the affected software until one is available. ## Is CVE-2020-1653 being exploited? There is no known exploitation of CVE-2020-1653 in the wild and no public exploit code. ## Other vulnerabilities in Juniper Junos - [CVE-2023-36845](https://insights.sbomify.com/CVE-2023-36845/): Juniper Junos OS EX Series and SRX Series PHP External Variable Modification (critical 9.8, exploited in the wild) - [CVE-2020-1631](https://insights.sbomify.com/CVE-2020-1631/): Juniper Junos OS Path Traversal (high 8.8, exploited in the wild) - [CVE-2025-21590](https://insights.sbomify.com/CVE-2025-21590/): Juniper Junos OS Improper Isolation or Compartmentalization (medium 6.7, exploited in the wild) - [CVE-2023-36851](https://insights.sbomify.com/CVE-2023-36851/): Juniper Junos OS SRX Series Missing Authentication for Critical Function (medium 5.3, exploited in the wild) - [CVE-2023-36844](https://insights.sbomify.com/CVE-2023-36844/): Juniper Junos OS EX Series PHP External Variable Modification (medium 5.3, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-1653 and fix it if it is affected. What it is: CVE-2020-1653 is a high-severity denial of service vulnerability in Juniper Junos, published on 17 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2020-1653 in the wild and no public exploit code. Affected product: Juniper Junos. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-1653/ (Markdown: https://insights.sbomify.com/CVE-2020-1653/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1653 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1653 - OSV: https://osv.dev/vulnerability/CVE-2020-1653 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-1653/ Summaries are generated and may contain mistakes; the official description above is the record.