diff --git a/dannytheway_personal/unbounded-copy-to-stack-buffer.cpp b/dannytheway_personal/unbounded-copy-to-stack-buffer.cpp
new file mode 100644
index 0000000000..2bf1656d51
--- /dev/null
+++ b/dannytheway_personal/unbounded-copy-to-stack-buffer.cpp
@@ -0,0 +1,153 @@
+#include <cstdio>
+#define BUFFER_SIZE 1024
+
+void test_001() {
+  char buf[BUFFER_SIZE];
+  // ruleid: unbounded-copy-to-stack-buffer
+  if (gets(buf) == NULL) {
+    // ...
+  }
+}
+
+void test_002() {
+  char buf[BUFFER_SIZE];
+  // ruleid: unbounded-copy-to-stack-buffer
+  if (std::gets(buf) == NULL) {
+    // ...
+  }
+}
+
+void test_003(void) {
+  char buf[BUFFER_SIZE];
+  // ruleid: unbounded-copy-to-stack-buffer
+  if (1 != fscanf(stdin, "%s", buf)) {
+    // ...
+  }
+}
+
+void test_003_valist(void) {
+  char buf[BUFFER_SIZE];
+  // ruleid: unbounded-copy-to-stack-buffer
+  if (1 != fscanf(stdin, "%d%d%s", 1, 2, buf)) {
+    // ...
+  }
+}
+
+void test_003_stmt(void) {
+  char buf[BUFFER_SIZE];
+  // ruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%d%d%s", 1, 2, buf);
+}
+
+void test_004(void) {
+  char buf[BUFFER_SIZE];
+  // ok: unbounded-copy-to-stack-buffer
+  if (1 != fscanf(stdin, "%d", buf)) {
+    // ...
+  }
+}
+
+void test_005(const char *name) {
+  char filename[128];
+  // ruleid: unbounded-copy-to-stack-buffer
+  sprintf(filename, "%s", name);
+}
+
+void test_006(const char *name) {
+  char filename[128];
+  // ok: unbounded-copy-to-stack-buffer
+  sprintf(filename, "%d", name);
+}
+
+void test_007(wchar_t *name) {
+  char filename[128];
+  // ruleid: unbounded-copy-to-stack-buffer
+  fwscanf(stdin, L"foo%sbar", filename);
+}
+
+void foo() {
+  char buf[64];
+  // ruleid: unbounded-copy-to-stack-buffer
+  gets(buf);
+}
+
+void foo() {
+  char buf[64];
+  // ok: unbounded-copy-to-stack-buffer
+  fgets(buf, 63, stdin);
+}
+
+void foo() {
+  char buf[128];
+  int n;
+  // ruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%dfoo%sbar", n, buf);
+  // ruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%sbar", n, buf);
+  // ruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "foo%s", n, buf);
+}
+
+void foo() {
+  char buf[128];
+  int n;
+  // ok: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%dfoo%10sbar", n, buf);
+}
+
+void foo() {
+  char buf[128];
+  int n;
+  // todoruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%dfoo%1024sbar", n, buf);
+}
+
+void foo() {
+  char buf[128];
+  // ruleid: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%sfoo%%s", buf);
+
+  // We don't scan all '%' characters so we don't understand that
+  // '%%%s' means "literal '%', followed by '%s'"
+  // todook: unbounded-copy-to-stack-buffer
+  fscanf(stdin, "%sfoo%%%s", buf);
+}
+
+void foo() {
+  char buf[64];
+  va_list ap;
+  va_start(ap, buf);
+  // ruleid: unbounded-copy-to-stack-buffer
+  vscanf("%s", ap);
+  va_end(ap);
+}
+
+void foo() {
+  char buf[64];
+  va_list ap;
+  va_start(ap, buf);
+  // ruleid: unbounded-copy-to-stack-buffer
+  vfscanf(stdin, "%s", ap);
+  va_end(ap);
+}
+
+void foo(char *str) {
+  char buf[0];
+  // ruleid: unbounded-copy-to-stack-buffer
+  sscanf(str, "%s", buf);
+
+  // todook: unbounded-copy-to-stack-buffer
+  sscanf("constant string", "%s", buf);
+
+  va_list ap;
+  va_start(ap, fmt);
+  // todoruleid: unbounded-copy-to-stack-buffer
+  vsscanf(str, "%s", buf);
+  va_end(ap);
+
+  va_list ap;
+  va_start(ap, fmt);
+  // ok: unbounded-copy-to-stack-buffer
+  vsscanf("constant string", "%s", buf);
+  va_end(ap);
+}
diff --git a/dannytheway_personal/unbounded-copy-to-stack-buffer.yaml b/dannytheway_personal/unbounded-copy-to-stack-buffer.yaml
new file mode 100644
index 0000000000..e6f5198b14
--- /dev/null
+++ b/dannytheway_personal/unbounded-copy-to-stack-buffer.yaml
@@ -0,0 +1,120 @@
+rules:
+- id: unbounded-copy-to-stack-buffer
+  languages:
+  - cpp
+  severity: ERROR
+  message: The function `$FUN` does not impose any size limitation to what it writes
+    to `$BUF`. That may lead to a stack buffer overflow if there is no validation
+    on the size of the input.
+  patterns:
+  - pattern-inside: |-
+      $TY $BUF[$SIZE];
+      ...
+  - pattern-either:
+    - patterns:
+      - pattern: <... $FUN($BUF, $STR) ...>
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: strcpy
+            - pattern: std::strcpy
+      - focus-metavariable: $FUN
+    - patterns:
+      - pattern: <... $FUN($BUF) ...>
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: gets
+            - pattern: std::gets
+      - focus-metavariable: $FUN
+    - patterns:
+      - pattern: <... $FUN($STDIN, "$FMT_STRING", ..., <... $BUF ...>) ...>
+      - metavariable-regex:
+          metavariable: $FMT_STRING
+          regex: ^(%l?s.*|.*[^%]%l?s.*)$
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: fscanf
+            - pattern: std::fscanf
+            - pattern: sscanf
+            - pattern: std::sscanf
+            - pattern: fwscanf
+            - pattern: std::fwscanf
+            - pattern: swscanf
+            - pattern: std::swscanf
+      - focus-metavariable: $FUN
+    - patterns:
+      - pattern: <... $FUN($BUF, "$FMT_STRING", ...) ...>
+      - metavariable-regex:
+          metavariable: $FMT_STRING
+          regex: ^(%l?s.*|.*[^%]%l?s.*)$
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: sprintf
+            - pattern: std::sprintf
+            - pattern: swprintf
+            - pattern: std::swprintf
+      - focus-metavariable: $FUN
+    - patterns:
+      - pattern: <... $FUN($SOURCE, "$FMT_STRING", $VA) ...>
+      - pattern-inside: |-
+          va_start($VA, $BUF);
+          ...
+          <... $FUN($SOURCE, "$FMT_STRING", $VA) ...>;
+      - metavariable-regex:
+          metavariable: $FMT_STRING
+          regex: ^(%l?s.*|.*[^%]%l?s.*)$
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: vfscanf
+            - pattern: std::vfscanf
+      - focus-metavariable: $FUN
+    - patterns:
+      - pattern: <... $FUN("$FMT_STRING", $VA) ...>
+      - pattern-inside: |-
+          va_start($VA, $BUF);
+          ...
+          <... $FUN("$FMT_STRING", $VA) ...>;
+      - metavariable-regex:
+          metavariable: $FMT_STRING
+          regex: ^(%l?s.*|.*[^%]%l?s.*)$
+      - metavariable-pattern:
+          metavariable: $FUN
+          patterns:
+          - pattern-either:
+            - pattern: vscanf
+            - pattern: std::vscanf
+      - focus-metavariable: $FUN
+  metadata:
+    likelihood: LOW
+    impact: HIGH
+    confidence: MEDIUM
+    category: security
+    subcategory:
+    - vuln
+    cert:
+    - C
+    - C++
+    - L1
+    - STR31-C
+    cwe:
+    - 'CWE-120: Buffer Copy without Checking Size of Input (''Classic Buffer Overflow'')'
+    display-name: Buffer Overflow
+    functional-categories:
+    - memory::sink::buffer-overflow
+    references:
+    - https://wiki.sei.cmu.edu/confluence/display/c/STR31-C.+Guarantee+that+storage+for+strings+has+sufficient+space+for+character+data+and+the+null+terminator
+    technology:
+    - cpp
+    license: Semgrep Rules License v1.0. For more details, visit semgrep.dev/legal/rules-license
+    vulnerability_class:
+    - Other
+  min-version: 1.59.0