High

Use-after-free in Linux kernel proc proc_lseek handling

IdentifiersCVE-2025-38653CWE-416· Use After Free

CVE-2025-38653 is a use-after-free vulnerability in the Linux kernel proc subsystem. The flaw is caused by directly checking the proc_lseek handler through pde->proc_ops->proc_lseek in proc_reg_open(), creating an unsafe lifetime gap during module removal. In an rmmod scenario, the underlying proc operations structure can become invalid while still being referenced, leading to a stale pointer dereference. The issue was identified as a gap remaining after an earlier fix for a related use-after-free in proc_get_inode(), and was resolved by applying the same handling model used for proc_read_iter and related proc operations.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can trigger a kernel-space use-after-free during interaction with affected proc entries while a backing module is being unloaded. This can result in kernel memory corruption and system instability, including denial of service through kernel crash or panic. Because the flaw occurs in kernel context, there is also potential for more severe consequences such as privilege escalation, although the available information does not confirm a demonstrated privilege-escalation exploit path.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by restricting module management to trusted administrators, minimizing or disabling unloading of proc-related kernel modules in production where operationally feasible, and limiting execution of untrusted local code on affected systems. These measures may reduce the likelihood of triggering the vulnerable rmmod race, but they do not fully remediate the flaw.

Remediation

Patch, then assume compromise.

Upgrade to a Linux kernel release that includes the fix for CVE-2025-38653, or apply the vendor backport provided in supported kernel packages. The remediation changes proc_lseek checking in proc_reg_open() to use the same safe treatment already applied to proc_read_iter and related handlers, eliminating the unsafe reference pattern during module teardown. After installing updated kernel packages, reboot into the fixed kernel.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

DebianDebian Linuxoperating_system

LinuxLinux Kerneloperating_system

SuseLinux Microoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

22 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

22 SOURCESView more in app

redhat accessNews

Jul 14, 2026

RHSA-2026:39371 - Security Advisory - Red Hat Customer Portal

Linux kernel vulnerability in proc handling related to proc_lseek checks.

redhat accessNews

Jun 4, 2026

RHSA-2026:23224 - Security Advisory - Red Hat Customer Portal

Linux kernel vulnerability in proc handling related to proc_lseek checks.

redhat accessNews

Jun 4, 2026

RHSA-2026:23329 - Security Advisory - Red Hat Customer Portal

A Linux kernel vulnerability in proc handling related to proc_lseek checks.

redhat accessNews

May 28, 2026

RHSA-2026:21556 - Security Advisory - Red Hat Customer Portal

Linux kernel vulnerability in proc handling related to proc_lseek checks.

+2 more in the timeline

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1