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CVE Record

CVE-2026-23148: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference

In the Linux kernel, the following vulnerability has been resolved: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference There is a race condition in nvmet_bio_done() that can cause a NULL pointer dereference in blk_cgroup_bio_start(): 1. nvmet_bio_done() is called when a bio completes 2. nvmet_req_complete() is called, which invokes req->ops->queue_response(req) 3. The queue_response callback can re-queue and re-submit the same request 4. The re-submission reuses the same inline_bio from nvmet_req 5. Meanwhile, nvmet_req_bio_put() (called after nvmet_req_complete) invokes bio_uninit() for inline_bio, which sets bio->bi_blkg to NULL 6. The re-submitted bio enters submit_bio_noacct_nocheck() 7. blk_cgroup_bio_start() dereferences bio->bi_blkg, causing a crash: BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode RIP: 0010:blk_cgroup_bio_start+0x10/0xd0 Call Trace: submit_bio_noacct_nocheck+0x44/0x250 nvmet_bdev_execute_rw+0x254/0x370 [nvmet] process_one_work+0x193/0x3c0 worker_thread+0x281/0x3a0 Fix this by reordering nvmet_bio_done() to call nvmet_req_bio_put() BEFORE nvmet_req_complete(). This ensures the bio is cleaned up before the request can be re-submitted, preventing the race condition.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can crash systems that run the NVMe target subsystem. The business impact is availability loss, not data theft, based on the supplied CVSS vector. Exposure is narrower than “all Linux servers”: it matters most where Linux is acting as an NVMe storage target reachable over a network.

Executive priority

Prioritize storage servers and infrastructure offering NVMe target services. This is a high availability risk that could interrupt storage service, but supplied evidence does not indicate confidentiality impact or confirmed exploitation.

Technical view

The issue is a race in nvmet_bio_done() where request completion can allow requeue and resubmission before inline_bio cleanup finishes. bio_uninit() can set bio->bi_blkg to NULL, leading blk_cgroup_bio_start() to dereference NULL and crash the kernel.

Likely exposure

Likely exposed systems are Linux hosts using nvmet/NVMe target functionality, especially network-accessible NVMe-oF storage targets. Ordinary Linux systems not using the NVMe target subsystem are less likely to be affected, but kernel version and module use should be verified against vendor guidance.

Exploitation context

The bundle reports CVSS 7.5 with network attack vector, no privileges, and high availability impact. KEV is false, and the provided sources do not state active exploitation or public exploit availability. Treat this as a denial-of-service risk until vendor advisories say more.

Researcher notes

The fix reorders nvmet_bio_done() so nvmet_req_bio_put() runs before nvmet_req_complete(), preventing reuse of an inline_bio while cleanup can NULL bi_blkg. Affected version metadata in the bundle should be reconciled with upstream stable commits and downstream kernel packages.

Mitigation direction

  • Apply a kernel update containing the referenced stable fixes.
  • Use distribution vendor advisories to map fixed package versions.
  • Restrict NVMe target access to trusted networks and initiators.
  • Disable nvmet/NVMe target services where not required.
  • Monitor for kernel crash signatures involving blk_cgroup_bio_start and nvmet.

Validation and detection

  • Inventory hosts with nvmet modules loaded or NVMe target configuration present.
  • Compare running kernels against vendor fixed versions or referenced commits.
  • Check logs for NULL pointer dereferences in blk_cgroup_bio_start.
  • Confirm NVMe target endpoints are not broadly internet reachable.
  • Verify patched systems no longer run an affected kernel build.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-23148 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-23148Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux431e58d56fcb5ff1f9eb630724a922e0d2a941df, 190f4c2c863af7cc5bb354b70e0805f06419c038, 190f4c2c863af7cc5bb354b70e0805f06419c038, 2e2028fcf924d1c6df017033c8d6e28b735a0508, 6.12.37, 6.15.6unaffected
LinuxLinux6.16, 0, 6.12.69, 6.18.9, 6.19affected
Weakness

CWE details

No CWE listed

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