high CVSS 7 EPSS <0.1%

CVE-2023-52480·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix race condition between session lookup and expire Thread A + Thread B ksmbd_session_lookup | smb2_sess_setup sess = xa_load | | | xa_erase(&conn->sessions, sess->id); | | ksmbd_session_destroy(sess) --> kfree(sess) | // UAF! | sess->last_active = jiffies | + This patch add rwsem to fix race condition between ksmbd_session_lookup and ksmbd_expire_session.

Severity
high
Software
Kernel
Fixed in
6.5.7
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 2% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2023-52480 scores 7 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 6.2

Until: 6.5.7

Fixed in: 6.5.7

How to fix this CVE

Update your Linux kernel to version 6.5.7 or later to address a use-after-free (UAF) vulnerability in the ksmbd subsystem. This race condition occurs when session lookup and expiration operations execute concurrently, potentially causing memory corruption. Apply the kernel update immediately, then reboot your system to activate the patched version.

sudo dnf update kernel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r — ensure it is 6.5.7 or newer
  2. Verify ksmbd is loaded: lsmod | grep ksmbd — if output is empty, ksmbd is not active on your system
  3. Check if SMB/CIFS shares are mounted: mount | grep cifs — note any active SMB connections
  4. After patching, confirm the new kernel is running: uname -r should show 6.5.7 or later

FAQ

What is CVE-2023-52480?

CVE-2023-52480 is a use-after-free vulnerability in the Linux kernel's ksmbd SMB server implementation. A race condition between concurrent session lookup and session expiration threads can cause one thread to access freed memory, potentially leading to privilege escalation or denial of service.

Is CVE-2023-52480 being actively exploited?

No, CVE-2023-52480 is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available.

What versions of Kernel are affected by CVE-2023-52480?

Linux kernel versions 6.2 through 6.5.6 are vulnerable. The fix was released in kernel 6.5.7.

How do I check if my server is vulnerable to CVE-2023-52480?

Run uname -r to check your kernel version. If the output is between 6.2 and 6.5.6 (inclusive), and ksmbd is enabled (lsmod | grep ksmbd returns output), your system is vulnerable.

Does Defensia detect CVE-2023-52480?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2023-52480 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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CVE-2026-52914CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix fragment reassembly length accounting batman-adv keeps a running payload length for queued fragments and uses it to validate a fragment chain before reassembly. That accounting currently allows the accumulated fragment length to be truncated during updates. As a result, malformed fragment chains can bypass the intended validation and drive reassembly with inconsistent length state, leading to a local denial of service. Fix the accounting by storing the accumulated length in a length-typed field and rejecting update overflows before the existing validation logic runs. The fix was verified against the original reproducer and against valid fragment reassembly paths.
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References

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