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CVE-2026-80951· NVD / CVE Program· CNA Linux

i3c: master: svc: bound IBI payload to the requested max_payload_len

In the Linux kernel, the following vulnerability has been resolved: i3c: master: svc: bound IBI payload to the requested max_payload_len svc_i3c_master_handle_ibi() reads the IBI payload from the RX FIFO into the IBI slot. The loop is bounded by the hardware FIFO size (SVC_I3C_FIFO_SIZE), not by the slot size. slot->data points into the IBI pool, which i3c_generic_ibi_alloc_pool() sizes at max_payload_len per slot. svc_i3c_master_request_ibi() only rejects a max_payload_len larger than SVC_I3C_FIFO_SIZE, so a driver can request a smaller one. mctp-i3c requests 1. Each readsb() then copies the controller RXCOUNT bytes (up to 31) with no check against the slot size. A device that sends more bytes than the slot holds writes past slot->data, an out-of-bounds write into the IBI pool. Bound the loop by dev->ibi->max_payload_len and clamp each read to the space left in the slot, the same way dw-i3c does. A device can still send more than the requested payload. Flush the leftover bytes from the RX FIFO so they do not leak into the next transfer.

—No exploit Fix available
Published
Sep 11, 2026
Updated
Sep 14, 2026
EPSS
0.2% · 11th percentile
CWE
—
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Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Affected systems

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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

    • 5.12affected
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before 7c099b0b292a68d0ef558527945dbfb756fbf893affected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before 7cc5ba756bc1cfffab9cb2695742f9f479dc73f7affected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before 35aa6730b8c5626b879a4e893fe664f59bf07d7faffected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before f296a0d5907bf88314dfda67245f7f69d1552470affected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before 5697d779577e2786ff3348ae9b77020ac0cf0aabaffected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before aac3c5aababc7fb69d5bf5b0cc52d308574e3a8caffected · git
    • dd3c52846d5954acd43f0e771689302f27dadc28 and later · before e2bda39d7f9f285ec803e200b5c1f17143d0b483affected · git
    • before 5.12not affected · semver
    • 5.15.221 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

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    40Plan

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 Linux35aa6730b8c5626b879a4e893fe664f59bf07d7fVendor (CNA)
Linux Linux5697d779577e2786ff3348ae9b77020ac0cf0aabVendor (CNA)
Linux Linux7c099b0b292a68d0ef558527945dbfb756fbf893Vendor (CNA)
Linux Linux7cc5ba756bc1cfffab9cb2695742f9f479dc73f7Vendor (CNA)
Linux Linuxaac3c5aababc7fb69d5bf5b0cc52d308574e3a8cVendor (CNA)
Linux Linuxe2bda39d7f9f285ec803e200b5c1f17143d0b483Vendor (CNA)
Linux Linuxf296a0d5907bf88314dfda67245f7f69d1552470Vendor (CNA)
debian:linux6.12.111-1 · Debian:13Package 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

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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

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Credits

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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.

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Bug bounty scope

No known public program.

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

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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.

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Change log

  1. Fix✗ → ✓

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References

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

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