diff --git a/meta/recipes-graphics/xwayland/xwayland/CVE-2026-33999.patch b/meta/recipes-graphics/xwayland/xwayland/CVE-2026-33999.patch
new file mode 100644
index 0000000000..cd3bf47397
--- /dev/null
+++ b/meta/recipes-graphics/xwayland/xwayland/CVE-2026-33999.patch
@@ -0,0 +1,49 @@
+From b024ae1749ee58c6fbf863b9a1f5dc440fee2e1b Mon Sep 17 00:00:00 2001
+From: Peter Harris <pharris2@rocketsoftware.com>
+Date: Thu, 15 Jan 2026 15:54:09 -0500
+Subject: [PATCH] xkb: fix buffer re-use in _XkbSetCompatMap
+
+If the "compat" buffer has previously been truncated, there will be
+unused space in the buffer. The code uses this space, but does not
+update the number of valid entries in the buffer.
+
+In the best case, this leads to the new compat entries being ignored. In the
+worst case, if there are any "skipped" compat entries, the number of
+valid entries will be corrupted, potentially leading to a buffer read
+overrun when processing a future request.
+
+Set the number of used "compat" entries when re-using previously
+allocated space in the buffer.
+
+CVE-2026-33999, ZDI-CAN-28593
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with TrendAI Zero Day Initiative
+
+Signed-off-by: Peter Harris <pharris2@rocketsoftware.com>
+Acked-by: Olivier Fourdan <ofourdan@redhat.com>
+Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2176>
+
+Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/xserver/-/commit/b024ae1749ee58c6fbf863b9a1f5dc440fee2e1b]
+CVE: CVE-2026-33999
+Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
+---
+ xkb/xkb.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/xkb/xkb.c b/xkb/xkb.c
+index 137d70d..2b9004a 100644
+--- a/xkb/xkb.c
++++ b/xkb/xkb.c
+@@ -3004,7 +3004,7 @@ _XkbSetCompatMap(ClientPtr client, DeviceIntPtr dev,
+                 return BadAlloc;
+             }
+         }
+-        else if (req->truncateSI) {
++        else if (req->truncateSI || req->firstSI + req->nSI > compat->num_si) {
+             compat->num_si = req->firstSI + req->nSI;
+         }
+         sym = &compat->sym_interpret[req->firstSI];
+-- 
+2.43.0
+
diff --git a/meta/recipes-graphics/xwayland/xwayland_23.2.5.bb b/meta/recipes-graphics/xwayland/xwayland_23.2.5.bb
index 362b110a0b..65f1ed2ae0 100644
--- a/meta/recipes-graphics/xwayland/xwayland_23.2.5.bb
+++ b/meta/recipes-graphics/xwayland/xwayland_23.2.5.bb
@@ -35,6 +35,7 @@ SRC_URI = "https://www.x.org/archive/individual/xserver/xwayland-${PV}.tar.xz \
            file://CVE-2025-62230-0001.patch \
            file://CVE-2025-62230-0002.patch \
            file://CVE-2025-62231.patch \
+           file://CVE-2026-33999.patch \
 "
 SRC_URI[sha256sum] = "33ec7ff2687a59faaa52b9b09aa8caf118e7ecb6aed8953f526a625ff9f4bd90"