CVE-2026-31617
What it is
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: validate minimum block_len in ncm_unwrap_ntb() The block_len read from the host-supplied NTB header is checked against ntb_max but has no lower bound. When block_len is smaller than opts->ndp_size, the bounds check of: ndp_index > (block_len - opts->ndp_size) will underflow producing a huge unsigned value that ndp_index can never exceed, defeating the check entirely. The same underflow occurs in the datagram index checks against block_len - opts->dpe_size. With those checks neutered, a malicious USB host can choose ndp_index and datagram offsets that point past the actual transfer, and the skb_put_data() copies adjacent kernel memory into the network skb. Fix this by rejecting block lengths that cannot hold at least the NTB header plus one NDP. This will make block_len - opts->ndp_size and block_len - opts->dpe_size both well-defined. Commit 8d2b1a1ec9f5 ("CDC-NCM: avoid overflow in sanity checking") fixed a related class of issues on the host side of NCM.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
- Exploit odds
- 0.1% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.1% in the next 30 days (EPSS).
- Severity: 5.5 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.1% · EPSS, next 30 days
- Weakness
- CWE-191
- Record status
- Modified
Affected
- Linux Kernel < 6.6.136
- Linux Kernel < 6.12.83
- Linux Kernel < 6.18.24
- Linux Kernel < 6.19.14
- Linux Kernel < 7.0.1
Attack profile CVSS 3.1 · 5.5
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-31617.md and follow it. Check whether this project is affected by CVE-2026-31617. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/0f156bb5334e588034ca68ac2ee92b23f66e56e7
- https://git.kernel.org/stable/c/6762f8a95772265dd0c2ffe7f400493f3115b135
- https://git.kernel.org/stable/c/74908b0318d1df1188457040b8714ff4d4b68126
- https://git.kernel.org/stable/c/8757a2593631443648218244b9788e193ae0fdc1
- https://git.kernel.org/stable/c/8f993d30b95dc9557a8a96ceca11abed674c8acb
- https://git.kernel.org/stable/c/d58ba8f6546232f8414f396c189297dbee03f1a7
References
- https://git.kernel.org/stable/c/068a7f2749fff6462a0a908ec415b885fe430f50
- https://git.kernel.org/stable/c/0f156bb5334e588034ca68ac2ee92b23f66e56e7
- https://git.kernel.org/stable/c/1425655c2870054c3ab4712e2b6dbdd331597ada
- https://git.kernel.org/stable/c/6762f8a95772265dd0c2ffe7f400493f3115b135
- https://git.kernel.org/stable/c/74908b0318d1df1188457040b8714ff4d4b68126
- https://git.kernel.org/stable/c/8757a2593631443648218244b9788e193ae0fdc1
- https://git.kernel.org/stable/c/8b3b7bd3c02f98634baaf36c7fc7ac915f6517ca
- https://git.kernel.org/stable/c/8f993d30b95dc9557a8a96ceca11abed674c8acb
- https://git.kernel.org/stable/c/d58ba8f6546232f8414f396c189297dbee03f1a7
- https://access.redhat.com/security/cve/CVE-2026-31617
- https://bugzilla.redhat.com/show_bug.cgi?id=2461448
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31617.json