memfd: deny writeable mappings when implying SEAL_WRITE
In the Linux kernel, the following vulnerability has been resolved: memfd: deny writeable mappings when implying SEAL_WRITE When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the implied seal is set after the check that makes sure the memfd can not have any writable mappings. This means one can use SEAL_EXEC to apply SEAL_WRITE while having writeable mappings. This breaks the contract that SEAL_WRITE provides and can be used by an attacker to pass a memfd that appears to be write sealed but can still be modified arbitrarily. Fix this by adding the implied seals before the call for mapping_deny_writable() is done.
CVE-2026-63952
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-2026-63952
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": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
"lessThan": "b3f4f82d1315f1439059a83d1c22c51a5b43d99e",
"versionType": "git"
},
{
"status": "affected",
"version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
"lessThan": "3be2a24f7f72ad7321ed6ad1715b956a4527bcf4",
"versionType": "git"
},
{
"status": "affected",
"version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
"lessThan": "0995d1f79aed8ccbf62056189dd53fd19726ea08",
"versionType": "git"
},
{
"status": "affected",
"version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
"lessThan": "555702282d4536a865dfffb1cd4f6028f196e7e8",
"versionType": "git"
},
{
"status": "affected",
"version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
"lessThan": "3b041514cb6eae45869b020f743c14d983363222",
"versionType": "git"
}
],
"programFiles": [
"mm/memfd.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.3"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"mm/memfd.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63952
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40909 · Revision 1
- Added to Heist Feed
- Publisher date