Описание
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Отчет
Red Hat rates this issue as Important impact. In xorg-x11-server and xorg-x11-server-Xwayland, CheckKeyTypes() does not clamp non-canonical keyboard types to XkbMaxShiftLevel. A local X client can set excessive shift levels and trigger stack buffer overflows in multiple code paths. This is an incomplete fix of CVE-2025-26597. Any local user who can connect to the X server display can attempt exploitation. Upstream fixed this in xorg-server 21.1.23 and xwayland 24.1.12.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | tigervnc | Affected | ||
| Red Hat Enterprise Linux 6 | xorg-x11-server | Out of support scope | ||
| Red Hat Enterprise Linux 10 | xorg-x11-server-Xwayland | Fixed | RHSA-2026:26566 | 22.06.2026 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | xorg-x11-server-Xwayland | Fixed | RHSA-2026:36798 | 08.07.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | xorg-x11-server | Fixed | RHSA-2026:36083 | 07.07.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | tigervnc | Fixed | RHSA-2026:46473 | 27.07.2026 |
| Red Hat Enterprise Linux 8 | xorg-x11-server-Xwayland | Fixed | RHSA-2026:26562 | 17.06.2026 |
| Red Hat Enterprise Linux 8 | xorg-x11-server | Fixed | RHSA-2026:26709 | 17.06.2026 |
| Red Hat Enterprise Linux 8 | tigervnc | Fixed | RHSA-2026:28923 | 24.06.2026 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | xorg-x11-server | Fixed | RHSA-2026:36792 | 08.07.2026 |
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Дополнительная информация
Статус:
EPSS
7.8 High
CVSS3
Связанные уязвимости
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels
A stack-based buffer overflow flaw was found in the X.Org X server and ...
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
EPSS
7.8 High
CVSS3