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

CVE-2026-98171: smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.53% (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. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 05762c5bc1cfdcac36747994fde2c04387a457f1, 1ed29f7a03417b405f38c09cfe04124883127b53, 491e33144dee872cffda207f6fcb09260728f803; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1.

Low priority for now. Upgrade to Linux Linux 05762c5bc1cfdcac36747994fde2c04387a457f1, 1ed29f7a03417b405f38c09cfe04124883127b53, 491e33144dee872cffda207f6fcb09260728f803; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1 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: smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs Fix several related bounds checking and pointer lifecycle issues in receive_encrypted_standard()'s handling of compound encrypted frames: - Clear next_buffer after assigning it to server->bigbuf. A stale next_buffer pointer can lead to a use-after-free on subsequent error paths. - Update pdu_length to the decrypted plaintext size (buf_size). Using the pre-decryption length allows NextCommand to point into stale ciphertext residue. - Reject next_cmd values smaller than MID_HEADER_SIZE(server). - Fix an integer overflow in the upper bound check by verifying pdu_length - next_cmd < MID_HEADER_SIZE(server), ensuring the trailing slice is large enough for a header.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Oct 6, 2026
Updated
Oct 30, 2026
EPSS
0.5% · 45th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CNA vs NVD score

NVD
—
CNA · Linux
8.8
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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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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

    • 4.19affected
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 1ed29f7a03417b405f38c09cfe04124883127b53affected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 7f022867ec9f0166a0b4400385bb601b1c6b2c75affected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 72eaef1f37a3b6bec11c342736834dc3707be3e4affected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 491e33144dee872cffda207f6fcb09260728f803affected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 8749946579708ea0d339034bb7f423a67dbe89cfaffected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 96c436e4b010711452b2872558938f4ef276492aaffected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 858d5ac22cb889266993e7670f9f0c4f4aeedd78affected · git
    • b24df3e30cbf48255db866720fb71f14bf9d2f39 and later · before 05762c5bc1cfdcac36747994fde2c04387a457f1affected · git
    • before 4.19not 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 6.12.113-1~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-2026-98169Oct 6, 2026 · smb: client: fix potential OOB read in smb3_enum_snapshots()
    28Monitor
  • ← EarlierCVE-2026-98170Oct 6, 2026 · smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs()
    0Monitor
  • Later →CVE-2026-98172Oct 6, 2026 · smb: client: fix smbd_connection leak on cifs_get_tcp_session() error
    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 Linux05762c5bc1cfdcac36747994fde2c04387a457f1Vendor (CNA)
Linux Linux1ed29f7a03417b405f38c09cfe04124883127b53Vendor (CNA)
Linux Linux491e33144dee872cffda207f6fcb09260728f803Vendor (CNA)
Linux Linux72eaef1f37a3b6bec11c342736834dc3707be3e4Vendor (CNA)
Linux Linux7f022867ec9f0166a0b4400385bb601b1c6b2c75Vendor (CNA)
Linux Linux858d5ac22cb889266993e7670f9f0c4f4aeedd78Vendor (CNA)
Linux Linux8749946579708ea0d339034bb7f423a67dbe89cfVendor (CNA)
Linux Linux96c436e4b010711452b2872558938f4ef276492aVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.158.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
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. TodayNov 10, 2026+35 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.
  • 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
Network
Attack complexity
Low
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:L/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— → 8.8
  2. Severity— → high
  3. Exploit maturity— → none
  4. 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