Linux Kernel up to 6.6.139/6.12.87/6.18.29/7.0.6 mpi_read_raw_from_sgl nbytes integer underflow

CVSS Meta Temp Score
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CTI Interest Score
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5.4$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.139/6.12.87/6.18.29/7.0.6. It has been classified as critical. This issue affects the function mpi_read_raw_from_sgl. This manipulation of the argument nbytes causes integer underflow. This vulnerability is handled as CVE-2026-43492. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.6.139/6.12.87/6.18.29/7.0.6 and classified as critical. Affected by this vulnerability is the function mpi_read_raw_from_sgl. The manipulation of the argument nbytes with an unknown input leads to a integer underflow vulnerability. The CWE definition for the vulnerability is CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl() Yiming reports an integer underflow in mpi_read_raw_from_sgl() when subtracting "lzeros" from the unsigned "nbytes". For this to happen, the scatterlist "sgl" needs to occupy more bytes than the "nbytes" parameter and the first "nbytes + 1" bytes of the scatterlist must be zero. Under these conditions, the while loop iterating over the scatterlist will count more zeroes than "nbytes", subtract the number of zeroes from "nbytes" and cause the underflow. When commit 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") originally introduced the bug, it couldn't be triggered because all callers of mpi_read_raw_from_sgl() passed a scatterlist whose length was equal to "nbytes". However since commit 63ba4d67594a ("KEYS: asymmetric: Use new crypto interface without scatterlists"), the underflow can now actually be triggered. When invoking a KEYCTL_PKEY_ENCRYPT system call with a larger "out_len" than "in_len" and filling the "in" buffer with zeroes, crypto_akcipher_sync_prep() will create an all-zero scatterlist used for both the "src" and "dst" member of struct akcipher_request and thereby fulfil the conditions to trigger the bug: sys_keyctl() keyctl_pkey_e_d_s() asymmetric_key_eds_op() software_key_eds_op() crypto_akcipher_sync_encrypt() crypto_akcipher_sync_prep() crypto_akcipher_encrypt() rsa_enc() mpi_read_raw_from_sgl() To the user this will be visible as a DoS as the kernel spins forever, causing soft lockup splats as a side effect. Fix it.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-43492 since 05/01/2026. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/22/2026).

The vulnerability scanner Nessus provides a plugin with the ID 315315 (Linux Distros Unpatched Vulnerability : CVE-2026-43492), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.140, 6.12.88, 6.18.30, 7.0.7 or 7.1-rc1 eliminates this vulnerability. Applying the patch 2aa77a18dc7f2670497fe3ee5acbeda0b57659e5/26d3a97ad46c7a9226ec04d4bf35bd4998a97d16/8637dfb4c1d8a7026ef681f2477c6de8b71c4003/30e513e755bb381afce6fb57cdc8694136193f22/8c2f1288250a90a4b5cabed5d888d7e3aeed4035 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (315315) and CERT Bund (WID-SEC-2026-1587). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • Open Source Linux Kernel

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.4

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Integer underflow
CWE: CWE-191 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 315315
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-43492

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.140/6.12.88/6.18.30/7.0.7/7.1-rc1
Patch: 2aa77a18dc7f2670497fe3ee5acbeda0b57659e5/26d3a97ad46c7a9226ec04d4bf35bd4998a97d16/8637dfb4c1d8a7026ef681f2477c6de8b71c4003/30e513e755bb381afce6fb57cdc8694136193f22/8c2f1288250a90a4b5cabed5d888d7e3aeed4035

Timelineinfo

05/01/2026 CVE reserved
05/19/2026 +18 days Advisory disclosed
05/19/2026 +0 days VulDB entry created
07/22/2026 +64 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-43492 (🔒)
GCVE (CVE): GCVE-0-2026-43492
GCVE (VulDB): GCVE-100-364621
CERT Bund: WID-SEC-2026-1587 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 05/19/2026 15:30
Updated: 07/22/2026 23:54
Changes: 05/19/2026 15:30 (59), 05/20/2026 04:22 (2), 06/26/2026 21:05 (10), 07/22/2026 23:54 (7)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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