vt: discard stale unicode buffer on alt screen exit after resize
In the Linux kernel, the following vulnerability has been resolved: vt: discard stale unicode buffer on alt screen exit after resize When enter_alt_screen() saves vc_uni_lines into vc_saved_uni_lines and sets vc_uni_lines to NULL, a subsequent console resize via vc_do_resize() skips reallocating the unicode buffer because vc_uni_lines is NULL. However, vc_saved_uni_lines still points to the old buffer allocated for the original dimensions. When leave_alt_screen() later restores vc_saved_uni_lines, the buffer dimensions no longer match vc_rows/vc_cols. Any operation that iterates over the unicode buffer using the current dimensions (e.g. csi_J clearing the screen) will access memory out of bounds, causing a kernel oops: BUG: unable to handle page fault for address: 0x0000002000000020 RIP: 0010:csi_J+0x133/0x2d0 The faulting address 0x0000002000000020 is two adjacent u32 space characters (0x20) interpreted as a pointer, read from the row data area past the end of the 25-entry pointer array in a buffer allocated for 80x25 but accessed with 240x67 dimensions. Fix this by checking whether the console dimensions changed while in the alternate screen. If they did, free the stale saved buffer instead of restoring it. The unicode screen will be lazily rebuilt via vc_uniscr_check() when next needed.
CVE-2026-31742
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-2026-31742
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": "c4efef65a46f610418a3f69149c51492d31c8591",
"lessThan": "891d790fdb5c96c6e1d2841e06ee6c360f2d1288",
"versionType": "git"
},
{
"status": "affected",
"version": "1cf66bd9127447c57295f5199029e8d8b47c6c67",
"lessThan": "428fdf55301e6c8fa5a36b426240797b1cf86570",
"versionType": "git"
},
{
"status": "affected",
"version": "5eb608319bb56464674a71b4a66ea65c6c435d64",
"lessThan": "40014493cece72a0be5672cd86763e53fb3ec613",
"versionType": "git"
}
],
"programFiles": [
"drivers/tty/vt/vt.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.18.20",
"lessThan": "6.18.22",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.19.10",
"lessThan": "6.19.12",
"versionType": "semver"
}
],
"programFiles": [
"drivers/tty/vt/vt.c"
],
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-31742
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #39991 · Revision 1
- Added to Heist Feed
- Publisher date