medium CVSS 6.7 EPSS <0.1%

CVE-2024-26828·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: cifs: fix underflow in parse_server_interfaces() In this loop, we step through the buffer and after each item we check if the size_left is greater than the minimum size we need. However, the problem is that "bytes_left" is type ssize_t while sizeof() is type size_t. That means that because of type promotion, the comparison is done as an unsigned and if we have negative bytes left the loop continues instead of ending.

Severity
medium
Software
Kernel
Fixed in
6.7.6
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 5% 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.

Affected versions

From: 6.7

Until: 6.7.6

Fixed in: 6.7.6

How to fix this CVE

Update the Linux kernel to version 6.7.6 or later to patch the buffer underflow vulnerability in the CIFS network filesystem parsing routine. This fix corrects a type promotion issue that could allow improper memory access during server interface enumeration. Apply the update immediately to systems using CIFS mounts, particularly in networked environments.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to display the currently installed kernel version and compare it against 6.7.6
  2. Execute 'grep CONFIG_CIFS /boot/config-$(uname -r)' to verify if CIFS support is compiled into the kernel
  3. Check 'mount | grep cifs' to identify any active CIFS mounts that could expose this vulnerability
  4. After patching, reboot the system with 'sudo reboot' and verify the new kernel version with 'uname -r' to confirm the update applied successfully

FAQ

What is CVE-2024-26828?

This vulnerability is a buffer underflow in the Linux kernel's CIFS (Common Internet File System) network filesystem parser. A type mismatch between signed and unsigned integers in the parse_server_interfaces() function allows negative buffer sizes to bypass validation checks, potentially leading to memory corruption or information disclosure.

Is CVE-2024-26828 being actively exploited?

No, this vulnerability is not currently being actively exploited in the wild according to CISA threat intelligence, and no public exploits have been disclosed.

What versions of Kernel are affected by CVE-2024-26828?

Linux kernel versions 6.7 through 6.7.5 are vulnerable. The issue was resolved in kernel 6.7.6 and all subsequent releases.

How do I check if my server is vulnerable to CVE-2024-26828?

Run 'uname -r' and check if the kernel version is between 6.7 and 6.7.5 inclusive. If CIFS is also enabled (verify with 'grep CONFIG_CIFS /boot/config-$(uname -r)'), the system is vulnerable.

Does Defensia detect CVE-2024-26828?

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-2024-26828 will appear in your dashboard with remediation steps.

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References

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