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CVE-2026-43492— lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于mpi_read_raw_from_sgl()函数中存在整数下溢问题，可能导致内存损坏。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.15% · P4

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 2d4d1eea540b27c72488fd1914674c42473d53df< a1793a48881ec8d26e9c79b0ee65753f1c6846a4 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 1abd50fc3cfa16fc2074a3c8c2729c50fd9d7043 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 6d63615c796c085b4984e3031b9fa77fffb47360 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 2aa77a18dc7f2670497fe3ee5acbeda0b57659e5 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 26d3a97ad46c7a9226ec04d4bf35bd4998a97d16 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 8637dfb4c1d8a7026ef681f2477c6de8b71c4003 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 30e513e755bb381afce6fb57cdc8694136193f22 affected
2d4d1eea540b27c72488fd1914674c42473d53df< 8c2f1288250a90a4b5cabed5d888d7e3aeed4035 affected
… +10 more rows
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I. Basic Information for CVE-2026-43492

Vulnerability Information
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Vulnerability Title
lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl()
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于mpi_read_raw_from_sgl()函数中存在整数下溢问题，可能导致内存损坏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 2d4d1eea540b27c72488fd1914674c42473d53df ~ a1793a48881ec8d26e9c79b0ee65753f1c6846a4 -
Linux Linux 4.4 -

II. Public POCs for CVE-2026-43492

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III. Intelligence Information for CVE-2026-43492

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Patches & Fixes for CVE-2026-43492 (8)

Same Patch Batch · Linux · 2026-05-19 · 3 CVEs total

CVE-2026-43493 9.8 CRITICAL crypto: pcrypt - Fix handling of MAY_BACKLOG requests
CVE-2026-43491 net: qrtr: ns: Limit the maximum server registration per node

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43492

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