Linux Kernel up to 6.12.108/6.18.49/7.2.3 nfsd nfsd4_ff_encode_layoutget out-of-bounds write

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.00+

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. It has been rated as very critical. The affected element is the function nfsd4_ff_encode_layoutget of the component nfsd. Performing a manipulation results in out-of-bounds write. This vulnerability is cataloged as CVE-2026-89674. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. This affects the function nfsd4_ff_encode_layoutget of the component nfsd. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget The XDR buffer size calculation in nfsd4_ff_encode_layoutget() has multiple errors that can result in either an out-of-bounds write or leaking uninitialized kernel memory to the client: - fh_len doesn't account for XDR padding on the file handle data - uid and gid lengths use "8 + len" but xdr_encode_opaque() actually writes "4 + xdr_align_size(len)" bytes - ds_len omits the flags and stats_collect_hint fields (8 bytes), while len's header constant overestimates by 8 bytes -- these partially cancel but leave a net mismatch The worst case occurs with short strings (e.g. uid=0, gid=0 with an odd-sized file handle), where the function writes up to 5 bytes past the reserved XDR buffer. Conversely, when string lengths happen to be 4-byte aligned, the reservation is too large and stale buffer content is sent to the client. Fix this by breaking out every encoded field explicitly in the ds_len calculation, using xdr_align_size() for all variable-length opaque fields, and correcting the header constants.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-89674 since 09/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch e7d9d23ecd9172f05b09bb678ff22db8e361c428/0380129b1373c437eb35401a174671c8888f4b80/c81cef6a805dec266c10fc4f83c93d6fcf1a2b43/f9868174af49d207fbaf0c5e055d088a983684af is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: e7d9d23ecd9172f05b09bb678ff22db8e361c428/0380129b1373c437eb35401a174671c8888f4b80/c81cef6a805dec266c10fc4f83c93d6fcf1a2b43/f9868174af49d207fbaf0c5e055d088a983684af

Timelineinfo

09/11/2026 CVE reserved
09/12/2026 +1 days Advisory disclosed
09/12/2026 +0 days VulDB entry created
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89674 (🔒)
GCVE (CVE): GCVE-0-2026-89674
GCVE (VulDB): GCVE-100-402969

Entryinfo

Created: 09/12/2026 02:17
Changes: 09/12/2026 02:17 (59)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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