GHSA-HMJM-JGV8-X76G
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: MSFT: validate evt_prefix_len against the response length
read_supported_features() only checks that the response covers the fixed part of struct msft_rp_read_supported_features, which is 11 bytes:
if (skb->len < sizeof(*rp)) {
bt_dev_err(hdev, "MSFT supported features length mismatch");
goto failed;
}
evt_prefix[] is a flexible array member and rp->evt_prefix_len is an unvalidated u8 taken straight out of that response, so
msft->evt_prefix = kmemdup(rp->evt_prefix, rp->evt_prefix_len,
GFP_KERNEL);
copies up to 255 bytes from a reply that may have carried none of them. What is copied is data the controller never sent, and it is then used to match incoming vendor events in msft_vendor_evt().
This is not an out-of-bounds access. An skb data allocation always has at least SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) bytes past the payload, which is more than the 255 byte maximum, so the read stays inside the allocation and KASAN does not report it. It is still a read of bytes the host was never given, with the length fully controlled by the controller.
Reject a response that is too short for the prefix it declares.
Verified with an emulated controller over /dev/vhci on a KASAN kernel, with vhci made to advertise an MSFT opcode the way btintel, btqca, btmtk and btrtl do unconditionally. A reply of exactly 11 bytes declaring evt_prefix_len = 255 reaches kmemdup and copies 255 bytes ("skb->len=11 evt_prefix_len=255", with the copied buffer dumped); since the reply ends at the fixed part, all 255 come from past the end of the response. No KASAN report is produced, as expected from the allocation slack described above. With this patch the response is rejected with "MSFT event prefix length mismatch" and msft->evt_prefix is left unset.
{
"affected": [],
"aliases": [
"CVE-2026-90251"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:21Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: MSFT: validate evt_prefix_len against the response length\n\nread_supported_features() only checks that the response covers the fixed\npart of struct msft_rp_read_supported_features, which is 11 bytes:\n\n\tif (skb-\u003elen \u003c sizeof(*rp)) {\n\t\tbt_dev_err(hdev, \"MSFT supported features length mismatch\");\n\t\tgoto failed;\n\t}\n\nevt_prefix[] is a flexible array member and rp-\u003eevt_prefix_len is an\nunvalidated u8 taken straight out of that response, so\n\n\tmsft-\u003eevt_prefix = kmemdup(rp-\u003eevt_prefix, rp-\u003eevt_prefix_len,\n\t\t\t\t GFP_KERNEL);\n\ncopies up to 255 bytes from a reply that may have carried none of them.\nWhat is copied is data the controller never sent, and it is then used to\nmatch incoming vendor events in msft_vendor_evt().\n\nThis is not an out-of-bounds access. An skb data allocation always has\nat least SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) bytes past the\npayload, which is more than the 255 byte maximum, so the read stays\ninside the allocation and KASAN does not report it. It is still a read\nof bytes the host was never given, with the length fully controlled by\nthe controller.\n\nReject a response that is too short for the prefix it declares.\n\nVerified with an emulated controller over /dev/vhci on a KASAN kernel,\nwith vhci made to advertise an MSFT opcode the way btintel, btqca, btmtk\nand btrtl do unconditionally. A reply of exactly 11 bytes declaring\nevt_prefix_len = 255 reaches kmemdup and copies 255 bytes\n(\"skb-\u003elen=11 evt_prefix_len=255\", with the copied buffer dumped); since\nthe reply ends at the fixed part, all 255 come from past the end of the\nresponse. No KASAN report is produced, as expected from the allocation\nslack described above. With this patch the response is rejected with\n\"MSFT event prefix length mismatch\" and msft-\u003eevt_prefix is left unset.",
"id": "GHSA-hmjm-jgv8-x76g",
"modified": "2026-09-17T18:31:57Z",
"published": "2026-09-17T18:31:57Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90251"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0079e1a944634ab2dc1c7cdec1144486d096407e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/21f539c59ed330b671d75fd119c5f659ff92fbd1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/52b1b3b4d403cbda1b70ce2385e1a71f166a87ba"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/620c2631cff490d14d0b9d56f185cc745806d6d7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/63562cfaea8a650fdb31ee8de21c32e3600be642"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7c2658023d839b651368a5b8b781bf9a817647cb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dce783a10e70f013410f5b583a29fc3286899629"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e804d54a5a99d99250490e68093eff7190472e6f"
}
],
"schema_version": "1.4.0",
"severity": []
}
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
Loading timeline…
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.