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NVD / CVE Program· CNA Linux

CVE-2025-39817: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare

Noroxi assessment

Priority: Monitor (action score 28/100)

  • 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: 0.16% (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 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6, 3.9, 568e7761279b99c6daa3002290fd6d8047ddb6d2; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1.

Low priority for now. Upgrade to Linux Linux 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6, 3.9, 568e7761279b99c6daa3002290fd6d8047ddb6d2; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1 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: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasan_check_range+0xe8/0x190 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8 __d_lookup_rcu_op_compare+0x178/0x218 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0 __arm64_sys_openat+0x120/0x1a0 If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename: T1 T2 lookup_open ->lookup simple_lookup d_add // invalid dentry is added to hash list lookup_open d_alloc_parallel __d_lookup_rcu __d_lookup_rcu_op_compare hlist_bl_for_each_entry_rcu // invalid dentry can be retrieved ->d_compare efivarfs_d_compare // oob Fix it by checking 'guid' before cmp.

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Sep 16, 2025
Updated
Oct 19, 2026
EPSS
0.1% · 6th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.1
CNA · Linux
7.1
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

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  • No public exploit code on record
  • A fix has been released

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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.

VendorProduct
linuxlinux kernel
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux11.0
  • linux linux kernel5.5 and later · before 5.10.242
  • linux linux kernel5.11 and later · before 5.15.191
  • linux linux kernel5.16 and later · before 6.1.150
  • linux linux kernel3.8.2 and later · before 5.4.298
  • linux linux kernel6.7 and later · before 6.12.45
  • linux linux kernel6.13 and later · before 6.16.5
  • linux linux kernel6.2 and later · before 6.6.104
  • linux linux kernel6.17

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

    • 688289c4b745c018b3449b4b4c5a2030083c8eaf, 3.9affected
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6affected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before 794399019301944fd6d2e0d7a51b3327e26c410eaffected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before 568e7761279b99c6daa3002290fd6d8047ddb6d2affected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7affected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before 925599eba46045930b850a98ae594d2e3028ac40affected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before c2925cd6207079c3f4d040d082515db78d63afbfaffected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before 71581a82f38e5a4d807d71fc1bb59aead80ccf95affected · git
    • da27a24383b2b10bf6ebd0db29b325548aafecb4 and later · before a6358f8cf64850f3f27857b8ed8c1b08cfc4685caffected · git
    • 3.8.2 and later · before 3.9affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-55.40.1.el10_06.12.0-55.40.1.el10_0
AlmaLinux:10kernel-docbefore 6.12.0-55.40.1.el10_06.12.0-55.40.1.el10_0
AlmaLinux:8bpftoolbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.81.1.el8_104.18.0-553.81.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.81.1.rt7.422.el8_104.18.0-553.81.1.rt7.422.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-39815Sep 16, 2025 · RISC-V: KVM: fix stack overrun when loading vlenb
    22Monitor
  • ← EarlierCVE-2025-39816Sep 16, 2025 · io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths
    22Monitor
  • Later →CVE-2025-39818Sep 16, 2025 · HID: intel-thc-hid: intel-thc: Fix incorrect pointer arithmetic in I2C regs save
    31Monitor

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 Linux0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6Vendor (CNA)
Linux Linux3.9Vendor (CNA)
Linux Linux568e7761279b99c6daa3002290fd6d8047ddb6d2Vendor (CNA)
Linux Linux71581a82f38e5a4d807d71fc1bb59aead80ccf95Vendor (CNA)
Linux Linux794399019301944fd6d2e0d7a51b3327e26c410eVendor (CNA)
Linux Linux925599eba46045930b850a98ae594d2e3028ac40Vendor (CNA)
Linux Linuxa6358f8cf64850f3f27857b8ed8c1b08cfc4685cVendor (CNA)
Linux Linuxc2925cd6207079c3f4d040d082515db78d63afbfVendor (CNA)
Linux Linuxd7f5e35e70507d10cbaff5f9e194ed54c4ee14f7Vendor (CNA)
azl3 kernel 6.6.96.2-2 on Azure Linux 3.06.6.104.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.05.15.200.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.153-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.4.0-150600.23.92.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-64kb6.4.0-150600.23.92.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-debug6.4.0-150600.23.92.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default6.4.0-150600.23.92.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default-base6.4.0-150600.23.92.1.150600.12.42.2 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-docs6.4.0-150600.23.92.1 · openSUSE:Leap 15.6Package registry (OSV)

+33

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.

No history yet (it accumulates with the daily EPSS job).

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

  • 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
none
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
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (10 more)

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

All records