Linux Kernel Privilege Escalation
CVE-2021-22600 is a high-severity double free vulnerability in Kernel from Linux kernel, with a CVSS 3.1 base score of 7.0 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 5.4.168, 5.10.88, 5.15.11 as the first without the flaw, so updating Kernel to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on April 11, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Kernel to 5.4.168 or 5.10.88 or 5.15.11 or 5.16-rc6, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.14.259 or 4.19.222 or 5.4.168 or 5.10.88, whichever matches your release line, or a later version.
- CISA's required action: Apply updates per vendor instructions.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux Kernel | Kernel | before 5.4.168; before 5.10.88; before 5.15.11; before 5.16-rc6 | 5.4.168, 5.10.88, 5.15.11, 5.16-rc6 |
| NetApp | 8300 Firmware | Not specified in the record | Not stated |
| NetApp | 8700 Firmware | Not specified in the record | Not stated |
| NetApp | A400 Firmware | Not specified in the record | Not stated |
| NetApp | C400 Firmware | Not specified in the record | Not stated |
| Linux | Linux Kernel | 4.14.175 up to, but not including, 4.14.259; 4.19.114 up to, but not including, 4.19.222; 5.4.29 up to, but not including, 5.4.168; 5.5.14 up to, but not including, 5.10.88; 5.11 up to, but not including, 5.15.11 | 4.14.259, 4.19.222, 5.4.168, 5.10.88, 5.15.11 |
| Debian | Debian Linux | 9.0; 10.0 | Not stated |
| NetApp | H410c Firmware | Not specified in the record | Not stated |
| NetApp | H300s Firmware | Not specified in the record | Not stated |
| NetApp | H500s Firmware | Not specified in the record | Not stated |
| NetApp | H700s Firmware | Not specified in the record | Not stated |
| NetApp | H410s Firmware | Not specified in the record | Not stated |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.6 | Medium | CNA (google.com) |
| CVSS 3.1 | 7.0 | High | NVD |
| CVSS 2.0 | 7.2 | High | NVD |
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
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2022/03/msg00012.htmlMailing List, Third Party Advisory
- security.netapp.com/advisory/ntap-20230110-0002/Third Party Advisory
- debian.org/security/2022/dsa-5096Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22600US Government Resource
Recent Double Free vulnerabilities
- 7.5 High severity
- 7.8 High severity
Apple Multiple Products Code Execution Exploited
- 8.8 High severity
Adobe Acrobat and Reader Double Free Exploited
- 8.8 High severity
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