CyberSecBulletin
CVE-2025-38346NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2025-38346 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 d064c68781c19f378af1ae741d9132d35d24b2bb, 8690cd3258455bbae64f809e1d3ee0f043661c71, 6805582abb720681dd1c87ff677f155dcf4e86c9 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 0.21% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to d064c68781c19f378af1ae741d9132d35d24b2bb or 8690cd3258455bbae64f809e1d3ee0f043661c71 or 6805582abb720681dd1c87ff677f155dcf4e86c9 or 03a162933c4a03b9f1a84f7d8482903c7e1e11bb, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.4.295 or 5.10.239 or 5.15.186 or 6.1.142, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxaba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, d064c68781c19f378af1ae741d9132d35d24b2bb; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, 8690cd3258455bbae64f809e1d3ee0f043661c71; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, 6805582abb720681dd1c87ff677f155dcf4e86c9; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, 03a162933c4a03b9f1a84f7d8482903c7e1e11bb; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, 83a692a9792aa86249d68a8ac0b9d55ecdd255fa; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, 8e89c17dc8970c5f71a3a991f5724d4c8de42d8c; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, f78a786ad9a5443a29eef4dae60cde85b7375129; aba4b5c22cbac296f4081a0476d0c55828f135b4 up to, but not including, f914b52c379c12288b7623bb814d0508dbe7481d; and 1 more rangesd064c68781c19f378af1ae741d9132d35d24b2bb, 8690cd3258455bbae64f809e1d3ee0f043661c71, 6805582abb720681dd1c87ff677f155dcf4e86c9, 03a162933c4a03b9f1a84f7d8482903c7e1e11bb, 83a692a9792aa86249d68a8ac0b9d55ecdd255fa, 8e89c17dc8970c5f71a3a991f5724d4c8de42d8c
LinuxLinux Kernel4.15 up to, but not including, 5.4.295; 5.5 up to, but not including, 5.10.239; 5.11 up to, but not including, 5.15.186; 5.16 up to, but not including, 6.1.142; 6.2 up to, but not including, 6.6.95; 6.7 up to, but not including, 6.12.35; 6.13 up to, but not including, 6.15.45.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.95, 6.12.35
DebianDebian Linux11.0Not 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 systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: ftrace: Fix UAF when lookup kallsym after ftrace disabled The following issue happens with a buggy module: BUG: unable to handle page fault for address: ffffffffc05d0218 PGD 1bd66f067 P4D 1bd66f067 PUD 1bd671067 PMD 101808067 PTE 0 Oops: Oops: 0000 [#1] SMP KASAN PTI Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS RIP: 0010:sized_strscpy+0x81/0x2f0 RSP: 0018:ffff88812d76fa08 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffffffc0601010 RCX: dffffc0000000000 RDX: 0000000000000038 RSI: dffffc0000000000 RDI: ffff88812608da2d RBP: 8080808080808080 R08: ffff88812608da2d R09: ffff88812608da68 R10: ffff88812608d82d R11: ffff88812608d810 R12: 0000000000000038 R13: ffff88812608da2d R14: ffffffffc05d0218 R15: fefefefefefefeff FS: 00007fef552de740(0000) GS:ffff8884251c7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc05d0218 CR3: 00000001146f0000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ftrace_mod_get_kallsym+0x1ac/0x590 update_iter_mod+0x239/0x5b0 s_next+0x5b/0xa0 seq_read_iter+0x8c9/0x1070 seq_read+0x249/0x3b0 proc_reg_read+0x1b0/0x280 vfs_read+0x17f/0x920 ksys_read+0xf3/0x1c0 do_syscall_64+0x5f/0x2e0 entry_SYSCALL_64_after_hwframe+0x76/0x7e The above issue may happen as follows: (1) Add kprobe tracepoint; (2) insmod test.ko; (3) Module triggers ftrace disabled; (4) rmmod test.ko; (5) cat /proc/kallsyms; --> Will trigger UAF as test.ko already removed; ftrace_mod_get_kallsym() ... strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN); ... The problem is when a module triggers an issue with ftrace and sets ftrace_disable. The ftrace_disable is set when an anomaly is discovered and to prevent any more damage, ftrace stops all text modification. The issue that happened was that the ftrace_disable stops more than just the text modification. When a module is loaded, its init functions can also be traced. Because kallsyms deletes the init functions after a module has loaded, ftrace saves them when the module is loaded and function tracing is enabled. This allows the output of the function trace to show the init function names instead of just their raw memory addresses. When a module is removed, ftrace_release_mod() is called, and if ftrace_disable is set, it just returns without doing anything more. The problem here is that it leaves the mod_list still around and if kallsyms is called, it will call into this code and access the module memory that has already been freed as it will return: strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN); Where the "mod" no longer exists and triggers a UAF bug.

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.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

Spotted an error? Tell us.