Linux: Use After Free
CVE-2024-26951 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 f52be46e3e6ecefc2539119784324f0cbc09620a, 710a177f347282eea162aec8712beb1f42d5ad87, b7cea3a9af0853fdbb1b16633a458f991dde6aac 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 0.23% 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 f52be46e3e6ecefc2539119784324f0cbc09620a or 710a177f347282eea162aec8712beb1f42d5ad87 or b7cea3a9af0853fdbb1b16633a458f991dde6aac or 13d107794304306164481d31ce33f8fdb25a9c04, whichever matches your release line, or a later version.
- Update SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to V1.1.1 or a later version.
- Update Linux Kernel to 5.10.215 or 5.15.154 or 6.1.84 or 6.6.24, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, f52be46e3e6ecefc2539119784324f0cbc09620a; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, 710a177f347282eea162aec8712beb1f42d5ad87; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, b7cea3a9af0853fdbb1b16633a458f991dde6aac; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, 13d107794304306164481d31ce33f8fdb25a9c04; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, 7bedfe4cfa38771840a355970e4437cd52d4046b; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, 302b2dfc013baca3dea7ceda383930d9297d231d; e7096c131e5161fa3b8e52a650d7719d2857adfd up to, but not including, 55b6c738673871c9b0edae05d0c97995c1ff08c4; 5.6 | f52be46e3e6ecefc2539119784324f0cbc09620a, 710a177f347282eea162aec8712beb1f42d5ad87, b7cea3a9af0853fdbb1b16633a458f991dde6aac, 13d107794304306164481d31ce33f8fdb25a9c04, 7bedfe4cfa38771840a355970e4437cd52d4046b, 302b2dfc013baca3dea7ceda383930d9297d231d |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | before V1.1.1 | V1.1.1 |
| Linux | Linux Kernel | 5.6 up to, but not including, 5.10.215; 5.11 up to, but not including, 5.15.154; 5.16 up to, but not including, 6.1.84; 6.2 up to, but not including, 6.6.24; 6.7 up to, but not including, 6.7.12; 6.8 up to, but not including, 6.8.3 | 5.10.215, 5.15.154, 6.1.84, 6.6.24, 6.7.12, 6.8.3 |
| Debian | Debian Linux | 10.0 | 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
- 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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: wireguard: netlink: check for dangling peer via is_dead instead of empty list If all peers are removed via wg_peer_remove_all(), rather than setting peer_list to empty, the peer is added to a temporary list with a head on the stack of wg_peer_remove_all(). If a netlink dump is resumed and the cursored peer is one that has been removed via wg_peer_remove_all(), it will iterate from that peer and then attempt to dump freed peers. Fix this by instead checking peer->is_dead, which was explictly created for this purpose. Also move up the device_update_lock lockdep assertion, since reading is_dead relies on that. It can be reproduced by a small script like: echo "Setting config..." ip link add dev wg0 type wireguard wg setconf wg0 /big-config ( while true; do echo "Showing config..." wg showconf wg0 > /dev/null done ) & sleep 4 wg setconf wg0 <(printf "[Peer]\nPublicKey=$(wg genkey)\n") Resulting in: BUG: KASAN: slab-use-after-free in __lock_acquire+0x182a/0x1b20 Read of size 8 at addr ffff88811956ec70 by task wg/59 CPU: 2 PID: 59 Comm: wg Not tainted 6.8.0-rc2-debug+ #5 Call Trace: <TASK> dump_stack_lvl+0x47/0x70 print_address_description.constprop.0+0x2c/0x380 print_report+0xab/0x250 kasan_report+0xba/0xf0 __lock_acquire+0x182a/0x1b20 lock_acquire+0x191/0x4b0 down_read+0x80/0x440 get_peer+0x140/0xcb0 wg_get_device_dump+0x471/0x1130
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/13d107794304306164481d31ce33f8fdb25a9c04
- git.kernel.org/stable/c/302b2dfc013baca3dea7ceda383930d9297d231d
- git.kernel.org/stable/c/55b6c738673871c9b0edae05d0c97995c1ff08c4
- git.kernel.org/stable/c/710a177f347282eea162aec8712beb1f42d5ad87
- git.kernel.org/stable/c/7bedfe4cfa38771840a355970e4437cd52d4046b
- git.kernel.org/stable/c/b7cea3a9af0853fdbb1b16633a458f991dde6aac
- git.kernel.org/stable/c/f52be46e3e6ecefc2539119784324f0cbc09620a
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2024/06/msg00017.htmlThird Party Advisory
Other references
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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