CVE-2026-31742
published 2026-05-01CVE-2026-31742: 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()…
PriorityP340high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.13%
2.8th percentile
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.
Affected
9 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | >= 1cf66bd9127447c57295f5199029e8d8b47c6c67 < 428fdf55301e6c8fa5a36b426240797b1cf86570 | 428fdf55301e6c8fa5a36b426240797b1cf86570 |
| linux | linux | >= 5eb608319bb56464674a71b4a66ea65c6c435d64 < 40014493cece72a0be5672cd86763e53fb3ec613 | 40014493cece72a0be5672cd86763e53fb3ec613 |
| linux | linux | >= 6.18.20 < 6.18.22 | 6.18.22 |
| linux | linux | >= 6.19.10 < 6.19.12 | 6.19.12 |
| linux | linux | >= c4efef65a46f610418a3f69149c51492d31c8591 < 891d790fdb5c96c6e1d2841e06ee6c360f2d1288 | 891d790fdb5c96c6e1d2841e06ee6c360f2d1288 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 6.18.20 < 6.18.22 | 6.18.22 |
| linux | linux_kernel | >= 6.19.10 < 6.19.12 | 6.19.12 |
CVSS provenance
nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat7.0MEDIUM
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GHSA
GHSA-gc3m-rhhg-qfw6: In the Linux kernel, the following vulnerability has been resolved:
vt: discard stale unicode buffer on alt screen exit after resize
When enter_alt_
ghsa_unreviewed·2026-05-01
CVE-2026-31742 [HIGH] GHSA-gc3m-rhhg-qfw6: In the Linux kernel, the following vulnerability has been resolved:
vt: discard stale unicode buffer on alt screen exit after resize
When enter_alt_
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
RI
Red Hat
kernel: vt: discard stale unicode buffer on alt screen exit after resize
vendor_redhat·2026-05-01·CVSS 7.0
CVE-2026-31742 [MEDIUM] CWE-131 kernel: vt: discard stale unicode buffer on alt screen exit after resize
kernel: vt: discard stale unicode buffer on alt screen exit after resize
A flaw was found in the Linux kernel. When a console is resized while in an alternate screen mode, the system may fail to properly update its internal buffer for unicode characters. This can lead to an out-of-bounds memory access when the alternate screen mode is exited, potentially causing a system crash (kernel oops) and resulting in a Denial of Service (DoS).
Package: kernel (Red Hat Enterprise Linux 10) - Affected
Package: kernel (Red Hat Enterprise Linux 6) - Not affected
Package: kernel (Red Hat Enterprise Linux 7) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 7) - Affected
Package: kernel (Red Hat Enterprise Linux 8) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 8) - Affected
Package
No detection rules found.
No public exploits indexed.
2026-05-01
Published