Linux KernelOperating system · Linux
CVE-2025-21804
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: PCI: rcar-ep: Fix incorrect variable used when calling devm_request_mem_region() The rcar_pcie_parse_outbound_ranges() uses the devm_request_mem_region() macro to request a needed resource. A string variable that lives on the stack is then used to store a dynamically computed resource name, which is then passed on as one of the macro arguments. This can lead to undefined behavior. Depending on the current contents of the memory, the manifestations of errors may vary. One possible output may be as follows: $ cat /proc/iomem 30000000-37ffffff : 38000000-3fffffff : Sometimes, garbage may appear after the colon. In very rare cases, if no NULL-terminator is found in memory, the system might crash because the string iterator will overrun which can lead to access of unmapped memory above the stack. Thus, fix this by replacing outbound_name with the name of the previously requested resource. With the changes applied, the output will be as follows: $ cat /proc/iomem 30000000-37ffffff : memory2 38000000-3fffffff : memory3 [kwilczynski: commit log]
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisThe code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.
General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
>= 5.8, < 5.10.235>= 5.11, < 5.15.179>= 5.16, < 6.1.129>= 6.2, < 6.6.76>= 6.7, < 6.12.13>= 6.13, < 6.13.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.10.2355.15.1796.1.129
5.10.235, 5.15.179, 6.1.129, or 6.6.76 (choose the latest stable release in your current major version branch)
- Identify the current running Linux kernel version using `uname -r`
- Determine which branch the current kernel falls into based on the affected version ranges (5.8-5.10.x, 5.11-5.15.x, 5.16-6.1.x, or 6.2-6.6.x)
- Obtain the updated kernel package for your distribution that corresponds to one of the fixed versions: 5.10.235, 5.15.179, 6.1.129, or 6.6.76
- Upgrade the kernel using your distribution's package manager (e.g., `apt-get dist-upgrade`, `yum update`, or `dnf upgrade`)
- Reboot the system to load the patched kernel
- Verify the fix by checking `/proc/iomem` output for the PCI device to confirm proper resource naming (e.g., memory2, memory3 instead of garbage)
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-21804 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-21804 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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