Add CVE-2026-13906 to bug 504613867 in CHANGELOG

Bug: 549271249
Change-Id: I03e82992d681c4f2a46e8585e451b104853a38b7

CHANGELOG

diff --git a/CHANGELOG b/CHANGELOG
index 578ecd4..fa08aac 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,4 +1,4 @@
-2026-08-24 v3.15.0
+2026-08-25 v3.15.0
   This release is ABI compatible with the last release.
 
   This release includes the fixes for all the security issues found by
@@ -56,7 +56,7 @@
       size
     * Bug 514816767: aomenc fails assertion check mi->bsize == bsize
     * Bug 504613867: Potential heap OOB read in
-      av1_int_pro_motion_estimation due to stale stride
+      av1_int_pro_motion_estimation due to stale stride (CVE-2026-13906)
     * Bug 503810640: Undefined behavior: NaN-to-int conversion in
       aom_noise_model_get_grain_parameters
     * Bug 503171639: Heap-buffer-overflow in