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CVE-2026-89968· NVD / CVE Program· CNA Linux

nvmet-tcp: reject unsolicited H2CData PDUs

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.82% (FIRST EPSS); higher than 56.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 02341ee424fb2eed16b5b8a9d247492e49335c21, 14beef7d4f123fb458fc9844aa74a071871dcca6, 1cbed7538946c99e585acefd11c9ba3a0bdbae05; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 02341ee424fb2eed16b5b8a9d247492e49335c21, 14beef7d4f123fb458fc9844aa74a071871dcca6, 1cbed7538946c99e585acefd11c9ba3a0bdbae05; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: reject unsolicited H2CData PDUs nvmet_tcp_handle_h2c_data_pdu() accepts an H2CData PDU after only checking that its TTAG is a valid in-range command index and that the command's data buffers are mapped. It never checks that the target has actually solicited that data by sending an R2T for the command. A remote host can abuse this. It submits a write command that takes the R2T path and, before the target transmits the R2T, sends an H2CData PDU for that command's tag. The data completes the command early, and when the command then fails synchronously (e.g. a length mismatch caught by nvmet_check_transfer_len()), it is completed a second time. Each completion calls nvmet_tcp_queue_response(), so the same command is added to queue->resp_list twice while it is still linked; the second llist_add() makes the node point to itself (lentry->next == lentry). nvmet_tcp_process_resp_list() then walks that self-referential node and adds the command to resp_send_list twice. With CONFIG_DEBUG_LIST this trips the "list_add double add" check (kernel BUG); without it the loop never terminates and the nvmet_tcp workqueue wedges (soft-lockup). It is remotely triggerable and needs no authentication on an allow_any_host subsystem. Track whether an R2T has been transmitted for a command and reject an H2CData PDU that arrives before it. The flag is cleared on command reuse (nvmet_tcp_get_cmd() zeroes cmd->flags) and stays set across the multiple H2CData PDUs of a single solicited transfer.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Sep 16, 2026
Updated
Oct 19, 2026
EPSS
0.8% · 56th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.0affected
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before 02341ee424fb2eed16b5b8a9d247492e49335c21affected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before cade124c06f8e738e3a0df285ed2e08953e6bfaaaffected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before 14beef7d4f123fb458fc9844aa74a071871dcca6affected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before 9fb527103e53fd43a8e802c2eca407869c204f7aaffected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before 2b71f9193e3d3a352920ba367f1a6db345249038affected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before cf1484d9a75de6809ef331e16f525aaa41b0e16daffected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before 1cbed7538946c99e585acefd11c9ba3a0bdbae05affected · git
    • 872d26a391da92ed8f0c0f5cb5fef428067b7f30 and later · before db62b35cbca052860c519cbcabe7650708528738affected · git
    • before 5.0not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89966Sep 16, 2026 · mm/hugetlb_cma: fix null nodemask dereference in hugetlb_cma_alloc_frozen_folio
    0Monitor
  • ← EarlierCVE-2026-89967Sep 16, 2026 · mm/migrate_device: avoid out-of-bounds writes for compound folios
    31Monitor
  • Later →CVE-2026-89969Sep 16, 2026 · nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux02341ee424fb2eed16b5b8a9d247492e49335c21Vendor (CNA)
Linux Linux14beef7d4f123fb458fc9844aa74a071871dcca6Vendor (CNA)
Linux Linux1cbed7538946c99e585acefd11c9ba3a0bdbae05Vendor (CNA)
Linux Linux2b71f9193e3d3a352920ba367f1a6db345249038Vendor (CNA)
Linux Linux9fb527103e53fd43a8e802c2eca407869c204f7aVendor (CNA)
Linux Linuxcade124c06f8e738e3a0df285ed2e08953e6bfaaVendor (CNA)
Linux Linuxcf1484d9a75de6809ef331e16f525aaa41b0e16dVendor (CNA)
Linux Linuxdb62b35cbca052860c519cbcabe7650708528738Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records