Linux KernelOperating system · Linux
CVE-2025-38544
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: rxrpc: Fix bug due to prealloc collision When userspace is using AF_RXRPC to provide a server, it has to preallocate incoming calls and assign to them call IDs that will be used to thread related recvmsg() and sendmsg() together. The preallocated call IDs will automatically be attached to calls as they come in until the pool is empty. To the kernel, the call IDs are just arbitrary numbers, but userspace can use the call ID to hold a pointer to prepared structs. In any case, the user isn't permitted to create two calls with the same call ID (call IDs become available again when the call ends) and EBADSLT should result from sendmsg() if an attempt is made to preallocate a call with an in-use call ID. However, the cleanup in the error handling will trigger both assertions in rxrpc_cleanup_call() because the call isn't marked complete and isn't marked as having been released. Fix this by setting the call state in rxrpc_service_prealloc_one() and then marking it as being released before calling the cleanup function.
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 analysisAttacker-controllable input can reach an assertion that aborts the process when it fails, so a check meant for debugging becomes a denial-of-service in production. A single crafted request takes the service down. The fix is to handle unexpected input gracefully on reachable paths rather than asserting on it.
General guidance for the reachable assertion 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
>= 4.9, < 6.6.99>= 6.7, < 6.12.39>= 6.13, < 6.15.7= 6.16CVSS 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 · scoped6.6.996.12.396.15.7
Upgrade to kernel version 6.7.0 (if on 6.6.x), 6.13.0 (if on 6.12.x), 6.15.8 (if on 6.15.x), or 6.16.1 (if on 6.16.x)
- Identify current kernel version using `uname -r`
- Determine which version range your current kernel falls into from the affected versions: >= 4.9 < 6.6.99, >= 6.7 < 6.12.39, >= 6.13 < 6.15.7, or = 6.16
- Obtain the patch from https://git.kernel.org/stable/c/432c5363cd6fe5a928bbc94524d28b05515684dd
- Apply the patch to the kernel source code, specifically modifying rxrpc_service_prealloc_one() to set the call state and mark the call as released before calling rxrpc_cleanup_call()
- Rebuild the Linux kernel with the applied fix
- Reboot into the new kernel
- Alternatively, upgrade to a fixed kernel version: 6.7.0 or later for the 6.7.x branch, 6.13.0 or later for the 6.13.x branch, 6.15.8 or later for the 6.15.x branch, or 6.16.1 or later for the 6.16.x branch
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-2025-38544 — 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-2025-38544 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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