Linux KernelOperating system · Linux
CVE-2025-37865
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: net: dsa: mv88e6xxx: fix -ENOENT when deleting VLANs and MST is unsupported Russell King reports that on the ZII dev rev B, deleting a bridge VLAN from a user port fails with -ENOENT: https://lore.kernel.org/netdev/[email protected]/ This comes from mv88e6xxx_port_vlan_leave() -> mv88e6xxx_mst_put(), which tries to find an MST entry in &chip->msts associated with the SID, but fails and returns -ENOENT as such. But we know that this chip does not support MST at all, so that is not surprising. The question is why does the guard in mv88e6xxx_mst_put() not exit early: if (!sid) return 0; And the answer seems to be simple: the sid comes from vlan.sid which supposedly was previously populated by mv88e6xxx_vtu_get(). But some chip->info->ops->vtu_getnext() implementations do not populate vlan.sid, for example see mv88e6185_g1_vtu_getnext(). In that case, later in mv88e6xxx_port_vlan_leave() we are using a garbage sid which is just residual stack memory. Testing for sid == 0 covers all cases of a non-bridge VLAN or a bridge VLAN mapped to the default MSTI. For some chips, SID 0 is valid and installed by mv88e6xxx_stu_setup(). A chip which does not support the STU would implicitly only support mapping all VLANs to the default MSTI, so although SID 0 is not valid, it would be sufficient, if we were to zero-initialize the vlan structure, to fix the bug, due to the coincidence that a test for vlan.sid == 0 already exists and leads to the same (correct) behavior. Another option which would be sufficient would be to add a test for mv88e6xxx_has_stu() inside mv88e6xxx_mst_put(), symmetric to the one which already exists in mv88e6xxx_mst_get(). But that placement means the caller will have to dereference vlan.sid, which means it will access uninitialized memory, which is not nice even if it ignores it later. So we end up making both modifications, in order to not rely just on the sid == 0 coincidence, but also to avoid having uninitialized structure fields which might get temporarily accessed.
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 analysisMemory or a resource is used before it has been initialised, so its contents are whatever happened to be there — sometimes leaking earlier data, sometimes values an attacker can influence. Behaviour becomes unpredictable and occasionally exploitable. Remediation is initialising every resource before use and ensuring initialisation happens on all code paths.
General guidance for the use of uninitialized resource 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
>= 5.18, < 6.1.135>= 6.2, < 6.6.88>= 6.7, < 6.12.25>= 6.13, < 6.14.4= 6.15
Debian LinuxOperating system
= 11.0CVSS 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 · scoped6.1.1356.6.886.12.25
Linux kernel >= 6.1.135, >= 6.6.88, >= 6.12.25, or >= 6.14.4 (depending on your current branch); Debian 11 patched kernel
- 1. Identify the currently running Linux kernel version using `uname -r`
- 2. For upstream Linux kernel: upgrade to kernel version 6.1.135 or later (if currently on 6.1.x), or 6.6.88 or later (if on 6.6.x), or 6.12.25 or later (if on 6.7-6.12.x), or 6.14.4 or later (if on 6.13.x)
- 3. For Debian 11 (Bullseye): apply the Debian kernel security update that incorporates this fix, or rebuild/upgrade to a patched kernel
- 4. After kernel upgrade, reboot the system to load the fixed kernel
- 5. Verify the fix is applied by checking the mv88e6xxx driver source in `/usr/src/linux/drivers/net/dsa/mv88e6xxx/chip.c` for the zero-initialization of `struct mv88e6xxx_vlan` and the `mv88e6xxx_has_stu()` check in `mv88e6xxx_mst_put()`
Generated from the published advisory — verify against the referenced sources before acting.
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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-2025-37865 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
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