lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl()
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
CVE-2026-43492
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-43492
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "a1793a48881ec8d26e9c79b0ee65753f1c6846a4",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "1abd50fc3cfa16fc2074a3c8c2729c50fd9d7043",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "6d63615c796c085b4984e3031b9fa77fffb47360",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "2aa77a18dc7f2670497fe3ee5acbeda0b57659e5",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "26d3a97ad46c7a9226ec04d4bf35bd4998a97d16",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "8637dfb4c1d8a7026ef681f2477c6de8b71c4003",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "30e513e755bb381afce6fb57cdc8694136193f22",
"versionType": "git"
},
{
"status": "affected",
"version": "2d4d1eea540b27c72488fd1914674c42473d53df",
"lessThan": "8c2f1288250a90a4b5cabed5d888d7e3aeed4035",
"versionType": "git"
}
],
"programFiles": [
"lib/crypto/mpi/mpicoder.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.140",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.88",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.30",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.7",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"lib/crypto/mpi/mpicoder.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-43492
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #28351 · Revision 1
- Added to Heist Feed
- Publisher date