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NVD / CVE Program· CNA Linux

CVE-2026-74513: dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 48c073f88c93707089a4214f21cb4c3de5aea6e4, 90b2166605a7476007f7c013521d30b0be557cac, a10ea943356b9d70c5616a0a06f6fa97cfdaccb1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 48c073f88c93707089a4214f21cb4c3de5aea6e4, 90b2166605a7476007f7c013521d30b0be557cac, a10ea943356b9d70c5616a0a06f6fa97cfdaccb1 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: dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister dibs_lo_attach_dmb(), dibs_lo_detach_dmb() and dibs_lo_unregister_dmb() look up the dmb_node under dmb_ht_lock, drop the lock and only then operate on the node's refcount. Nothing keeps the node alive across that window: __dibs_lo_unregister_dmb() removes the node from the hash table under the write lock and immediately frees it. A concurrent final put can therefore free the node between the lookup and the refcount operation: CPU0 (attach) CPU1 (owner unregisters) read_lock_bh(&dmb_ht_lock) find dmb_node (refcnt == 1) read_unlock_bh(&dmb_ht_lock) refcount_dec_and_test() 1 -> 0 write_lock_bh(&dmb_ht_lock) hash_del(&dmb_node->list) write_unlock_bh(&dmb_ht_lock) kfree(dmb_node) refcount_inc_not_zero(&dmb_node->refcnt) <-- use-after-free The same window exists for the refcount_dec_and_test() calls in the detach and unregister paths. Close the race structurally by making hash table membership and the refcount transitions atomic with respect to each other: - Perform the final refcount_dec_and_test() and hash_del() in a single dmb_ht_lock write-side critical section, in both the unregister and the detach path. Freeing the node still happens after the lock is dropped, which is safe because a node whose refcount reached zero has left the hash table and can no longer be found. - This establishes the invariant that any node found in the hash table holds at least one reference, and that the final reference can only be dropped under the write lock. dibs_lo_attach_dmb() can thus take its reference with a plain refcount_inc() while still holding the read lock; refcount_inc_not_zero() is no longer needed. __dibs_lo_unregister_dmb() no longer touches the hash table and is renamed to dibs_lo_free_dmb() accordingly. Note: commit cc21191b584c ("dibs: Move data path to dibs layer") moved the code to its current location; the race was introduced earlier by commit c3a910f2380f ("net/smc: implement DMB-merged operations of loopback-ism"). Tested SMC-D via ISM and dibs loopback.

Published
Aug 15, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 2th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
7.8
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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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

    • 6.10affected
    • c3a910f2380fe294d14e42af66af3d3eed8fecbf and later · before 90b2166605a7476007f7c013521d30b0be557cacaffected · git
    • c3a910f2380fe294d14e42af66af3d3eed8fecbf and later · before c0837aeace96152d14b17fdd19d70102b6631a7daffected · git
    • c3a910f2380fe294d14e42af66af3d3eed8fecbf and later · before 48c073f88c93707089a4214f21cb4c3de5aea6e4affected · git
    • c3a910f2380fe294d14e42af66af3d3eed8fecbf and later · before a10ea943356b9d70c5616a0a06f6fa97cfdaccb1affected · git
    • before 6.10not affected · semver
    • 6.12.114 and later · up to and including 6.12.*not affected · semver
    • 6.18.44 and later · up to and including 6.18.*not affected · semver
    • 7.1.8 and later · up to and including 7.1.*not affected · semver
    • 7.2 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:13linuxbefore 6.12.115-26.12.115-2
Debian:14linuxbefore 7.1.8-17.1.8-1

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-2026-74510Aug 15, 2026 · Bluetooth: mgmt: fix UAF in pair command cancellation
    31Monitor
  • ← EarlierCVE-2026-74512Aug 15, 2026 · audit: fix potential use-after-free in audit_del_rule()
    31Monitor
  • Later →CVE-2026-74515Aug 15, 2026 · KVM: s390: pci: Reject adapter interrupt forwarding if already enabled
    35Monitor

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 Linux48c073f88c93707089a4214f21cb4c3de5aea6e4Vendor (CNA)
Linux Linux90b2166605a7476007f7c013521d30b0be557cacVendor (CNA)
Linux Linuxa10ea943356b9d70c5616a0a06f6fa97cfdaccb1Vendor (CNA)
Linux Linuxc0837aeace96152d14b17fdd19d70102b6631a7dVendor (CNA)
debian:linux6.12.115-2 · Debian:13Package registry (OSV)
debian:linux7.1.8-1 · Debian:14Package 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

References

Show all references (3 more)

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

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