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NVD / CVE Program· CNA Linux

CVE-2026-90193: mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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: 0.20% (FIRST EPSS).
  • Fixed version: Linux Linux 3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c, 8b8de6400c86937ed57d680d06d716e167b381de, aa482273f32117c3adeba9b1cc945e0b5d33722d.

Low priority for now. Upgrade to Linux Linux 3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c, 8b8de6400c86937ed57d680d06d716e167b381de, aa482273f32117c3adeba9b1cc945e0b5d33722d 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: mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler qcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while holding chan->lock. Under PREEMPT_RT, spin_lock_irqsave() is converted to an rt_spinlock (rtmutex-based), which tracks ownership and can sleep. The callback chain triggered by mbox_chan_received_data() eventually reaches mailbox_clear_channel() -> mbox_send_message() -> add_to_rbuf(), which attempts to re-acquire the same chan->lock. Since rtmutex detects the re-entrant lock attempt by the same owner, the thread blocks waiting for a lock it already holds, causing a permanent deadlock. This deadlock manifests as 'irq/N-apss_cpucp_mbox' stuck in D state with the following call trace: rt_spin_lock -> mbox_send_message -> mailbox_clear_channel -> scmi_rx_callback -> mbox_chan_received_data [<- held chan->lock here] Fix by saving chan->cl locally and clearing the HW interrupt register inside the lock, then invoking mbox_chan_received_data() after releasing the lock. This preserves the mutual exclusion for chan->cl access while avoiding the lock re-entrancy that causes the PREEMPT_RT deadlock.

—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 11th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

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

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Noroxi analysis

What does it mean in your environment?

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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

    • 6.11affected
    • 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 and later · before aa482273f32117c3adeba9b1cc945e0b5d33722daffected · git
    • 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 and later · before 8b8de6400c86937ed57d680d06d716e167b381deaffected · git
    • 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 and later · before e40b3edeaf25cd09e9c88edb1ef99373ca37593baffected · git
    • 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 and later · before 3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69caffected · git
    • before 6.11not affected · semver
    • 6.12.110 and later · up to and including 6.12.*not affected · semver
    • 6.18.52 and later · up to and including 6.18.*not affected · semver
    • 7.2.6 and later · up to and including 7.2.*not affected · semver
    • 7.3 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
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-2026-90191Sep 17, 2026 · mailbox: riscv-sbi-mpxy: validate RPMI notification lengths
    33Monitor
  • ← EarlierCVE-2026-90192Sep 17, 2026 · mailbox: qcom-cpucp: handle NULL data in send_data callback
    0Monitor
  • Later →CVE-2026-90194Sep 17, 2026 · ACPI: scan: fix bus ID cleanup on device_add() failures
    0Monitor

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 Linux3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69cVendor (CNA)
Linux Linux8b8de6400c86937ed57d680d06d716e167b381deVendor (CNA)
Linux Linuxaa482273f32117c3adeba9b1cc945e0b5d33722dVendor (CNA)
Linux Linuxe40b3edeaf25cd09e9c88edb1ef99373ca37593bVendor (CNA)
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

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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.

Change log

  1. Fix✗ → ✓

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References

Show all references (3 more)

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

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