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NVD / CVE Program· CNA Linux

CVE-2026-93787: smb: client: bound dirent name against end of SMB response in cifs_filldir

Noroxi assessment

Priority: Monitor (action score 32/100)

  • 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: 0.34% (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 03003506c86f90312b0966283662c42fcab66e4b, 4cb3d79beee0fecc739ce07af915d503f29ae557, 6e3b965267b7313903baba2739992b1e2e92d540; 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 03003506c86f90312b0966283662c42fcab66e4b, 4cb3d79beee0fecc739ce07af915d503f29ae557, 6e3b965267b7313903baba2739992b1e2e92d540; 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: bound dirent name against end of SMB response in cifs_filldir cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST / FIND_NEXT response using a length (de.namelen) supplied by the server. The kmalloc'd SMB response buffer is bounded, but nothing checks that de.name + de.namelen still lies inside that buffer before the eventual filldir64() -> verify_dirent_name() -> memchr() reads namelen bytes. A hostile SMB1 server that returns an oversized FileNameLength in a directory entry therefore causes memchr() to read past the end of the response slab buffer. Reachable from any user who can list a directory on a CIFS mount served by an attacker-controlled server (getdents64() on the mounted directory): BUG: KASAN: slab-out-of-bounds in memchr+0x71/0x80 Read of size 1 at addr ffff88800e0640cc by task poc/115 Call Trace: dump_stack_lvl+0x64/0x80 print_report+0xce/0x620 kasan_report+0xec/0x120 memchr+0x71/0x80 filldir64+0x4c/0x6a0 cifs_filldir.constprop.0+0x9bb/0x1e00 cifs_readdir+0x2101/0x3380 iterate_dir+0x19c/0x520 __x64_sys_getdents64+0x126/0x210 do_syscall_64+0x107/0x5a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Pass the end-of-response pointer down to cifs_filldir() and reject entries whose name would extend past that boundary. This bug was discovered by Artiphishell's vTriage pipeline, which generated a userspace reproducer (an emulated hostile SMB1 server plus a getdents64() client) that reliably triggers the KASAN report on an unpatched kernel. The fix below was drafted with the Claude coding assistant; a userspace reproducer is available on request.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Sep 24, 2026
Updated
Oct 3, 2026
EPSS
0.3% · 28th percentile
CWE
—

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CNA vs NVD score

NVD
—
CNA · Linux
8.1
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

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4cb3d79beee0fecc739ce07af915d503f29ae557affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before cf87ef1e62ed31a439064cef69d6eec38c68bd92affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 6e3b965267b7313903baba2739992b1e2e92d540affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 03003506c86f90312b0966283662c42fcab66e4baffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6affected · git
    • before 2.6.12not affected · semver
    • 6.1.189 and later · up to and including 6.1.*not affected · semver
    • 6.6.158 and later · up to and including 6.6.*not affected · semver
    • 6.12.111 and later · up to and including 6.12.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.181.1.el8_104.18.0-553.181.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10
AlmaLinux:8kernel-rt-modulesbefore 4.18.0-553.181.1.rt7.522.el8_104.18.0-553.181.1.rt7.522.el8_10

+26

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-2026-93785Sep 24, 2026 · cifs: validate idmap key payload length
    0Monitor
  • ← EarlierCVE-2026-93786Sep 24, 2026 · ksmbd: preserve VFS inherited POSIX ACL mask
    32Monitor
  • Later →CVE-2026-93788Sep 24, 2026 · wifi: iwlwifi: acpi: validate WGDS table revision index
    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 Linux03003506c86f90312b0966283662c42fcab66e4bVendor (CNA)
Linux Linux4cb3d79beee0fecc739ce07af915d503f29ae557Vendor (CNA)
Linux Linux6e3b965267b7313903baba2739992b1e2e92d540Vendor (CNA)
Linux Linuxcf87ef1e62ed31a439064cef69d6eec38c68bd92Vendor (CNA)
Linux Linuxf8cf09a53a0dc1da298e9dd0ba5f21710cf119d6Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.158.1-1 · Release NotesMicrosoft (MSRC)
almalinux:bpftool4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-devel4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-doc4.18.0-553.181.1.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)
rocky linux:kernel0:5.14.0-687.64.1.el9_8 · Rocky Linux:9Package registry (OSV)
suse:kernel-64kb6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-default6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-default-base6.4.0-150600.23.143.1.150600.12.66.3 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-docs6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-livepatch-SLE15-SP6_Update_331-150600.13.5.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-obs-build6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-source6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-syms6.4.0-150600.23.143.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)

+1

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

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
none
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
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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