# What is CVE-2021-22600? > CVE-2021-22600 is a high-severity flaw (CVSS 7.0) in Linux kernel, published on 26 January 2022. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 6.6%. If you run an affected version, patch it first. Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-22600 ## At a glance - **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list. - **Precursor Intelligence risk score:** 74 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes. - **Severity:** High (CVSS 7.0 out of 10) - **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited - **Chance of use in the next 30 days:** 6.6% (latest exploit-likelihood forecast) - **Published:** 26 January 2022 - **Record last updated:** 24 February 2025 - **Main product:** Linux kernel - **Affected products:** 12 ## What is CVE-2021-22600? In plain terms An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### The official description A double free bug in packet_set_ring() in net/packet/af_packet.c can be exploited by a local user through crafted syscalls to escalate privileges or deny service. We recommend upgrading kernel past the effected versions or rebuilding past ec6af094ea28f0f2dda1a6a33b14cd57e36a9755 ### What kind of flaw is it? - CWE-415: Double Free ### How an attack on it works - Where an attacker can be: Already on the device - How hard it is to pull off: Hard: conditions must line up - Login needed first: An ordinary user account - Does someone have to click: No, nobody has to do anything - What an attacker gets: Can read data, change data and take it offline Severity vector: `CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H` ## Is CVE-2021-22600 being exploited? Yes Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 6.6%. Exploit likelihood over the last 7 days: 6.6%, 6.6%, 6.6%, 6.6%, 6.6%, 6.6%, 6.6%. ### Timeline - 26 January 2022: Published - 24 February 2025: Record last updated ### How Precursor Intelligence ranks it CVE-2021-22600 scores **74 out of 100 (High)**, with the action "Emergency patch". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2021-22600? The published record lists 12 products. Versions are as published: "4.14.175 to before 4.14.259" means from 4.14.175 up to, but not including, 4.14.259. - [Linux kernel](https://www.precursorintelligence.com/product/linux/linux_kernel) by [Linux](https://www.precursorintelligence.com/vendors/linux) (Operating system): 4.14.175 to before 4.14.259, 4.19.114 to before 4.19.222, 5.4.29 to before 5.4.168, 5.5.14 to before 5.10.88, 5.11 to before 5.15.11 - [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 9.0, 10.0 - [H300s](https://www.precursorintelligence.com/product/netapp/h300s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified - [H300s Firmware](https://www.precursorintelligence.com/product/netapp/h300s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified - [H410c](https://www.precursorintelligence.com/product/netapp/h410c) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified - [H410c Firmware](https://www.precursorintelligence.com/product/netapp/h410c_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified - [H410s](https://www.precursorintelligence.com/product/netapp/h410s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified - [H410s Firmware](https://www.precursorintelligence.com/product/netapp/h410s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified - [H500s](https://www.precursorintelligence.com/product/netapp/h500s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified - [H500s Firmware](https://www.precursorintelligence.com/product/netapp/h500s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified - [H700s](https://www.precursorintelligence.com/product/netapp/h700s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified - [H700s Firmware](https://www.precursorintelligence.com/product/netapp/h700s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified ## How do I fix CVE-2021-22600? 1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance. ### References - [git.kernel.org](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=ec6af094ea28f0f2dda1a6a33b14cd57e36a9755) (Mailing list, Patch) - [lists.debian.org](https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html) (Mailing list, Third-party advisory) - [security.netapp.com](https://security.netapp.com/advisory/ntap-20230110-0002/) (Third-party advisory) - [debian.org](https://www.debian.org/security/2022/dsa-5096) (Third-party advisory) ## Questions ### What is CVE-2021-22600? CVE-2021-22600 is a high-severity flaw in Linux kernel, published on 26 January 2022. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### How serious is CVE-2021-22600? It scores 7.0 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-22600 is 74 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list. ### Is CVE-2021-22600 being exploited? Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 6.6%. ### Which versions does CVE-2021-22600 affect? For Linux kernel: 4.14.175 to before 4.14.259, 4.19.114 to before 4.19.222, 5.4.29 to before 5.4.168, 5.5.14 to before 5.10.88, 5.11 to before 5.15.11. The record lists 12 products in all, each with its versions, under "Who is affected" on this page. ### How do I fix CVE-2021-22600? Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in. ## Does CVE-2021-22600 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact