Linux: Use After Free
CVE-2022-49479 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions ef7f9f894cfd0b2e471206409a529af4a26ddd55, ddd426d72aca4054045a9bd3b80a4ce1d398f11f, fcfe1b5e162bf473c1d47760962cec8523c00466 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.31% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to ef7f9f894cfd0b2e471206409a529af4a26ddd55 or ddd426d72aca4054045a9bd3b80a4ce1d398f11f or fcfe1b5e162bf473c1d47760962cec8523c00466, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.17.14 or 5.18.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | bd1e3e7b693c17a04e7d2bd9119daa482b7c7720 up to, but not including, ef7f9f894cfd0b2e471206409a529af4a26ddd55; bd1e3e7b693c17a04e7d2bd9119daa482b7c7720 up to, but not including, ddd426d72aca4054045a9bd3b80a4ce1d398f11f; bd1e3e7b693c17a04e7d2bd9119daa482b7c7720 up to, but not including, fcfe1b5e162bf473c1d47760962cec8523c00466; 5.16 | ef7f9f894cfd0b2e471206409a529af4a26ddd55, ddd426d72aca4054045a9bd3b80a4ce1d398f11f, fcfe1b5e162bf473c1d47760962cec8523c00466 |
| Linux | Linux Kernel | 5.16 up to, but not including, 5.17.14; 5.18 up to, but not including, 5.18.3 | 5.17.14, 5.18.3 |
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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: mt76: fix tx status related use-after-free race on station removal There is a small race window where ongoing tx activity can lead to a skb getting added to the status tracking idr after that idr has already been cleaned up, which will keep the wcid linked in the status poll list. Fix this by only adding status skbs if the wcid pointer is still assigned in dev->wcid, which gets cleared early by mt76_sta_pre_rcu_remove
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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