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NVD / CVE Program· CNA Linux

CVE-2026-99274: smb: client: fix fiemap wild read on empty truncated response

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: 0.15% (FIRST EPSS).
  • Fixed version: Linux Linux 31f6dbb29fe17fa9595c7e8b19fd92915b03a4ca, 4a426ca5be7e3dedbe76575b967db04fbf01136f, 8e0d425b808c367f5033eb72aa4528ae18473627.

Low priority for now. Upgrade to Linux Linux 31f6dbb29fe17fa9595c7e8b19fd92915b03a4ca, 4a426ca5be7e3dedbe76575b967db04fbf01136f, 8e0d425b808c367f5033eb72aa4528ae18473627 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 fiemap wild read on empty truncated response smb3_fiemap() treats -E2BIG from SMB2_ioctl() as a truncated range blob and loops for the next chunk. If the server reports STATUS_BUFFER_OVERFLOW with OutputCount == 0, SMB2_ioctl() returns -E2BIG with out_data == NULL and out_data_len == 0, and the existing length checks accept the empty result. The loop then evaluates next = out_data[num - 1].file_offset + ... with num == 0, reading 16 bytes before NULL. Reject a truncated range blob that contains no range, so the resume offset is never computed from an empty response. Also require the last range in a truncated blob to advance the resume offset without overflowing, and to stay within the requested range; a malicious or broken server could otherwise make no progress or underflow len and loop forever. Free the previous response buffer before retrying. Reproduced on 6.6.87.2 with a malicious SMB2 server that answers FSCTL_QUERY_ALLOCATED_RANGES with STATUS_BUFFER_OVERFLOW and OutputCount == 0; an FS_IOC_FIEMAP ioctl on the mount oopses in cifs_fiemap() with CR2 = fffffffffffffff8. The code path is unchanged on mainline.

—No exploit Fix available
Published
Nov 7, 2026
Updated
Nov 10, 2026
EPSS
0.1% · 4th 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 · 0.1%

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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

    • 5.2affected
    • 2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4 and later · before 8e0d425b808c367f5033eb72aa4528ae18473627affected · git
    • 2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4 and later · before 4a426ca5be7e3dedbe76575b967db04fbf01136faffected · git
    • 2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4 and later · before 31f6dbb29fe17fa9595c7e8b19fd92915b03a4caaffected · git
    • 2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4 and later · before f5baa17a0f316c235d61623ac8e8fb32c2b3c0ccaffected · git
    • before 5.2not affected · semver
    • 6.12.117 and later · up to and including 6.12.*not affected · semver
    • 6.18.61 and later · up to and including 6.18.*not affected · semver
    • 7.3.2 and later · up to and including 7.3.*not affected · semver
    • 7.4-rc1 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:12linuxfrom 0—

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-2026-99272Nov 7, 2026 · smb: client: validate the data area in SMB2_read()
    0Monitor
  • ← EarlierCVE-2026-99273Nov 7, 2026 · ksmbd: reserve space for the UTF-16 terminator in stream info
    0Monitor
  • Later →CVE-2026-99275Nov 7, 2026 · smb: client: reject short SESSION_SETUP responses
    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 Linux31f6dbb29fe17fa9595c7e8b19fd92915b03a4caVendor (CNA)
Linux Linux4a426ca5be7e3dedbe76575b967db04fbf01136fVendor (CNA)
Linux Linux8e0d425b808c367f5033eb72aa4528ae18473627Vendor (CNA)
Linux Linuxf5baa17a0f316c235d61623ac8e8fb32c2b3c0ccVendor (CNA)

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 11, 2026+4 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

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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.

—

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✗ → ✓
  2. Exploit maturity— → none

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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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