medium CVSS 5.5 EPSS <0.1%

CVE-2021-47444·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read In commit e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid corruption test") the function connector_bad_edid() started assuming that the memory for the EDID passed to it was big enough to hold `edid[0x7e] + 1` blocks of data (1 extra for the base block). It completely ignored the fact that the function was passed `num_blocks` which indicated how much memory had been allocated for the EDID. Let's fix this by adding a bounds check. This is important for handling the case where there's an error in the first block of the EDID. In that case we will call connector_bad_edid() without having re-allocated memory based on `edid[0x7e]`.

Severity
medium
Software
Kernel
Fixed in
5.14.14
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 3% 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: 5.11

Until: 5.14.14

Fixed in: 5.14.14

How to fix this CVE

Update your Linux kernel to version 5.14.14 or later to resolve a memory bounds checking vulnerability in the EDID validation function. This vulnerability could allow local attackers to trigger a denial of service by exploiting improper handling of Extended Display Identification Data blocks. Ensure your system is running a patched kernel version and reboot to apply changes.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check your currently running kernel version; vulnerable versions are 5.11.x through 5.14.13
  2. Verify if the DRM subsystem is active on your system by checking 'lsmod | grep drm' to confirm the graphics driver stack is loaded
  3. Search kernel logs for EDID parsing errors with 'dmesg | grep -i edid' to identify if bad EDID data triggered the vulnerable code path
  4. After patching, reboot the system and confirm the new kernel version with 'uname -r' to ensure the fix is active

FAQ

What is CVE-2021-47444?

This vulnerability occurs in the Linux kernel's DRM (Direct Rendering Manager) EDID validation routine, where a bounds check was missing when processing Extended Display Identification Data. An attacker could provide malformed EDID to trigger memory access beyond allocated buffer boundaries, causing a denial of service.

Is CVE-2021-47444 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available, though it remains a local privilege escalation risk requiring authentication.

What versions of Kernel are affected by CVE-2021-47444?

Linux kernel versions 5.11 through 5.14.13 are vulnerable; the fix is included in kernel 5.14.14 and later.

How do I check if my server is vulnerable to CVE-2021-47444?

Run 'uname -r' and compare your kernel version against the vulnerable range 5.11-5.14.13; if your version falls in this range, your system requires patching.

Does Defensia detect CVE-2021-47444?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47444 will appear in your dashboard with remediation steps.

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References

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