Microsoft security update for CVE-2025-37865 — azl3 kernel
🔗 CVE IDs covered (1)
📋 Microsoft's advisory
EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-37865. This page also shows what EchelonGraph holds for CVE-2025-37865, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.
🎯 Affected products2
- azl3 kernel 6.6.85.1-4 on Azure Linux 3.0
- azl3 kernel 6.6.92.2-1 on Azure Linux 3.0
✅ Updates Microsoft lists: 1 update
1 row: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.
| KB article | Update | Fixed build |
|---|---|---|
| — | Security Update | 6.6.92.2-1 |
🧭 EchelonGraph on CVE-2025-37865
- EchelonGraph score
- 5.5 MEDIUM
- CISA KEV
- Not listed
- Fix status
- A fix is available — apply it.
Description from the CVE record (CVE.org), as published by its numbering authority
In 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.
Published by kernel.org, the CVE Numbering Authority that assigned CVE-2025-37865, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).