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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98173: smb: client: fix use-after-free of iface in cifs_try_adding_channels()

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: 0.32% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
  • Fixed version: Linux Linux c941f1ebfd26f683de81091473f3596a218abff0, d034e836eefd7ce75e588f7031cffbeec594f5ac, e99040e5e9c60441e6b4725e1a7b88c3106ae903; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to Linux Linux c941f1ebfd26f683de81091473f3596a218abff0, d034e836eefd7ce75e588f7031cffbeec594f5ac, e99040e5e9c60441e6b4725e1a7b88c3106ae903; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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: smb: client: fix use-after-free of iface in cifs_try_adding_channels() cifs_try_adding_channels() iterates ses->iface_list with list_for_each_entry_safe_from(), which captures the next entry (niface) under iface_lock. The loop body then drops iface_lock for the whole duration of cifs_ses_add_channel(). A concurrent interface refresh (SMB3_request_interfaces() -> parse_server_interfaces()) marks all ifaces inactive and removes and frees any that are not re-advertised via list_del() + kref_put(), where release_iface() is a bare kfree(). Since niface typically has no channel holding a reference, the list reference is its last and it can be freed inside the unlocked window. On continue, the iterator advance step then dereferences niface->iface_head.next, and the loop body reads iface->rdma_capable/is_active, both on freed memory. Fix this by never keeping an unreferenced list pointer across the unlocked window. Each channel attempt now re-scans the list from the head under iface_lock, takes a kref on the selected candidate, and passes only that referenced candidate to cifs_ses_add_channel(). weight_fulfilled still tracks selection progress, so restarting the scan preserves the original weighted distribution and the weight_fulfilled-before-kref_put ordering on the failure path. Add a per-pass attempts cap so a flapping interface refresh cannot keep the inner loop spinning within a single tries increment.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Oct 6, 2026
Updated
Oct 21, 2026
EPSS
0.3% · 25th 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 · 0.3%

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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When you'll hear from us

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  • when exploit code appears or is weaponized
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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

    • 5.19affected
    • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec and later · before ee0d8f83d68f6e6509f092c997ccab3c8c801538affected · git
    • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec and later · before c941f1ebfd26f683de81091473f3596a218abff0affected · git
    • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec and later · before e99040e5e9c60441e6b4725e1a7b88c3106ae903affected · git
    • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec and later · before ec36b38e65596950e6c29bed7dfc90b98707c19caffected · git
    • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec and later · before d034e836eefd7ce75e588f7031cffbeec594f5acaffected · git
    • before 5.19not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.112 and later · up to and including 6.12.*not affected · semver
    • 6.18.54 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.113-1~deb12u16.12.113-1~deb12u1
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.2.8-17.2.8-1
openSUSE:Tumbleweedkernel-sourcebefore 7.2.10-1.17.2.10-1.1

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-2026-98171Oct 6, 2026 · smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs
    35Monitor
  • ← EarlierCVE-2026-98172Oct 6, 2026 · smb: client: fix smbd_connection leak on cifs_get_tcp_session() error
    0Monitor
  • Later →CVE-2026-98174Oct 6, 2026 · smb: client: fix rlist race and missing initialization
    30Monitor

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 Linuxc941f1ebfd26f683de81091473f3596a218abff0Vendor (CNA)
Linux Linuxd034e836eefd7ce75e588f7031cffbeec594f5acVendor (CNA)
Linux Linuxe99040e5e9c60441e6b4725e1a7b88c3106ae903Vendor (CNA)
Linux Linuxec36b38e65596950e6c29bed7dfc90b98707c19cVendor (CNA)
Linux Linuxee0d8f83d68f6e6509f092c997ccab3c8c801538Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.12.113-1 · Debian:13Package registry (OSV)
debian:linux7.2.8-1 · Debian:14Package registry (OSV)
debian:linux-6.126.12.113-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.2.10-1.1 · openSUSE:TumbleweedPackage 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.

  1. Published
  2. Fix recordedsame day
  3. TodayOct 30, 2026+24 d
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).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • Special conditions such as timing or configuration are required.

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
Network
Attack complexity
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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.

Change log

  1. CVSS— → 7.5
  2. Severity— → high
  3. Exploit maturity— → none
  4. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records