Linux: Use After Free
CVE-2022-49934 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 6eb181a64fdabf10be9e54de728876667da20255, e0ff39448cea654843744c72c6780293c5082cb1, 78a07732fbb0934d14827d8f09b9aa6a49ee1aa9 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 0.24% 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 6eb181a64fdabf10be9e54de728876667da20255 or e0ff39448cea654843744c72c6780293c5082cb1 or 78a07732fbb0934d14827d8f09b9aa6a49ee1aa9 or 9ad48cbf8b07f10c1e4a7a262b32a9179ae9dd2d, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.9.330 or 4.14.295 or 4.19.260 or 5.4.215, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 6eb181a64fdabf10be9e54de728876667da20255; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, e0ff39448cea654843744c72c6780293c5082cb1; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 78a07732fbb0934d14827d8f09b9aa6a49ee1aa9; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 9ad48cbf8b07f10c1e4a7a262b32a9179ae9dd2d; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 4abc8c07a065ecf771827bde3c63fbbe4aa0c08b; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 5d20c6f932f2758078d0454729129c894fe353e7; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, c0445feb80a4d0854898118fa01073701f8d356b; 6ea0a69ca21bbddab5b3979c2190013b0263e749 up to, but not including, 60deb9f10eec5c6a20252ed36238b55d8b614a2c; and 1 more ranges | 6eb181a64fdabf10be9e54de728876667da20255, e0ff39448cea654843744c72c6780293c5082cb1, 78a07732fbb0934d14827d8f09b9aa6a49ee1aa9, 9ad48cbf8b07f10c1e4a7a262b32a9179ae9dd2d, 4abc8c07a065ecf771827bde3c63fbbe4aa0c08b, 5d20c6f932f2758078d0454729129c894fe353e7 |
| Linux | Linux Kernel | 3.19 up to, but not including, 4.9.330; 4.10 up to, but not including, 4.14.295; 4.15 up to, but not including, 4.19.260; 4.20 up to, but not including, 5.4.215; 5.5 up to, but not including, 5.10.142; 5.11 up to, but not including, 5.15.66; 5.16 up to, but not including, 5.19.8; 6.0 | 4.9.330, 4.14.295, 4.19.260, 5.4.215, 5.10.142, 5.15.66 |
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
- LowNo special conditions are needed; the attack works reliably.
- 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:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: Fix UAF in ieee80211_scan_rx() ieee80211_scan_rx() tries to access scan_req->flags after a null check, but a UAF is observed when the scan is completed and __ieee80211_scan_completed() executes, which then calls cfg80211_scan_done() leading to the freeing of scan_req. Since scan_req is rcu_dereference()'d, prevent the racing in __ieee80211_scan_completed() by ensuring that from mac80211's POV it is no longer accessed from an RCU read critical section before we call cfg80211_scan_done().
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/4abc8c07a065ecf771827bde3c63fbbe4aa0c08b
- git.kernel.org/stable/c/5d20c6f932f2758078d0454729129c894fe353e7
- git.kernel.org/stable/c/60deb9f10eec5c6a20252ed36238b55d8b614a2c
- git.kernel.org/stable/c/6eb181a64fdabf10be9e54de728876667da20255
- git.kernel.org/stable/c/78a07732fbb0934d14827d8f09b9aa6a49ee1aa9
- git.kernel.org/stable/c/9ad48cbf8b07f10c1e4a7a262b32a9179ae9dd2d
- git.kernel.org/stable/c/c0445feb80a4d0854898118fa01073701f8d356b
- git.kernel.org/stable/c/e0ff39448cea654843744c72c6780293c5082cb1
Recent Use After Free vulnerabilities
- 8.8 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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