diff --git a/library/helpers/addIPv4TransitionAddresses.test.ts b/library/helpers/addIPv4TransitionAddresses.test.ts
new file mode 100644
index 000000000..acc1a7908
--- /dev/null
+++ b/library/helpers/addIPv4TransitionAddresses.test.ts
@@ -0,0 +1,45 @@
+import * as t from "tap";
+import { addIPv4TransitionAddresses } from "./addIPv4TransitionAddresses";
+
+t.test("it adds transition mechanism addresses for IPv4 entries", async (t) => {
+  t.same(addIPv4TransitionAddresses(["127.0.0.1"]), [
+    "127.0.0.1",
+    "64:ff9b::127.0.0.1/128",
+    "64:ff9b:1::127.0.0.1/128",
+    "::127.0.0.1/128",
+    "2002:7f00:1::/48",
+  ]);
+});
+
+t.test("it adjusts the prefix length for an IPv4 CIDR range", async (t) => {
+  t.same(addIPv4TransitionAddresses(["10.0.0.0/8"]), [
+    "10.0.0.0/8",
+    "64:ff9b::10.0.0.0/104",
+    "64:ff9b:1::10.0.0.0/104",
+    "::10.0.0.0/104",
+    "2002:a00:0::/24",
+  ]);
+});
+
+t.test("it handles empty array", async (t) => {
+  t.same(addIPv4TransitionAddresses([]), []);
+});
+
+t.test("it handles only IPv6 addresses", async (t) => {
+  t.same(addIPv4TransitionAddresses(["2001:db8::1", "::1"]), [
+    "2001:db8::1",
+    "::1",
+  ]);
+});
+
+t.test("it handles a mix of IPv4 and IPv6 addresses", async (t) => {
+  t.same(addIPv4TransitionAddresses(["2001:db8::1", "127.0.0.1", "::1"]), [
+    "2001:db8::1",
+    "127.0.0.1",
+    "::1",
+    "64:ff9b::127.0.0.1/128",
+    "64:ff9b:1::127.0.0.1/128",
+    "::127.0.0.1/128",
+    "2002:7f00:1::/48",
+  ]);
+});
diff --git a/library/helpers/addIPv4TransitionAddresses.ts b/library/helpers/addIPv4TransitionAddresses.ts
new file mode 100644
index 000000000..a23026f98
--- /dev/null
+++ b/library/helpers/addIPv4TransitionAddresses.ts
@@ -0,0 +1,18 @@
+import { mapIPv4To6to4 } from "./mapIPv4To6to4";
+import { mapIPv4WithIPv6Prefix } from "./mapIPv4WithIPv6Prefix";
+
+/**
+ * Adds IPv4-in-IPv6 transition mechanism versions for all IPv4 addresses in the array.
+ */
+export function addIPv4TransitionAddresses(ips: string[]): string[] {
+  const ipv4Addresses = ips.filter((ip) => !ip.includes(":"));
+
+  return ips.concat(
+    ipv4Addresses.flatMap((ip) => [
+      mapIPv4WithIPv6Prefix(ip, "64:ff9b::", 96), // Well-Known NAT64 prefix (RFC 6052)
+      mapIPv4WithIPv6Prefix(ip, "64:ff9b:1::", 96), // Local-Use NAT64 prefix (RFC 8215)
+      mapIPv4WithIPv6Prefix(ip, "::", 96), // IPv4-compatible IPv6 address (RFC 4291)
+      mapIPv4To6to4(ip), // 6to4 (RFC 3056)
+    ])
+  );
+}
diff --git a/library/helpers/mapIPv4To6to4.test.ts b/library/helpers/mapIPv4To6to4.test.ts
new file mode 100644
index 000000000..97b07b186
--- /dev/null
+++ b/library/helpers/mapIPv4To6to4.test.ts
@@ -0,0 +1,21 @@
+import * as t from "tap";
+import { mapIPv4To6to4 } from "./mapIPv4To6to4";
+
+t.test("it maps a single IPv4 address to its 6to4 form", async (t) => {
+  t.equal(mapIPv4To6to4("127.0.0.1"), "2002:7f00:1::/48");
+  t.equal(mapIPv4To6to4("10.0.0.1"), "2002:a00:1::/48");
+  t.equal(mapIPv4To6to4("192.168.0.1"), "2002:c0a8:1::/48");
+  t.equal(mapIPv4To6to4("8.8.8.8"), "2002:808:808::/48");
+});
+
+t.test("it adjusts the prefix length for an IPv4 CIDR range", async (t) => {
+  t.equal(mapIPv4To6to4("10.0.0.0/8"), "2002:a00:0::/24");
+  t.equal(mapIPv4To6to4("192.168.0.0/16"), "2002:c0a8:0::/32");
+});
+
+t.test("it does not pad hex groups that have leading zeros", async (t) => {
+  // JS drops leading zeros when converting to hex (e.g. 1 -> "1", not "0001"),
+  // which is still valid, unambiguous IPv6 group notation.
+  t.equal(mapIPv4To6to4("0.1.0.1"), "2002:1:1::/48");
+  t.equal(mapIPv4To6to4("0.0.0.0/0"), "2002:0:0::/16");
+});
diff --git a/library/helpers/mapIPv4To6to4.ts b/library/helpers/mapIPv4To6to4.ts
new file mode 100644
index 000000000..bcecfde39
--- /dev/null
+++ b/library/helpers/mapIPv4To6to4.ts
@@ -0,0 +1,15 @@
+import { splitCIDR } from "./splitCIDR";
+
+/**
+ * Maps an IPv4 address to its 6to4 (RFC 3056) IPv6 representation.
+ * 6to4 embeds the IPv4 address as two hex groups right after the 2002:: prefix.
+ * e.g. mapIPv4To6to4("10.0.0.1") -> "2002:a00:1::/128"
+ * e.g. mapIPv4To6to4("10.0.0.0/8") -> "2002:a00:0::/24"
+ */
+export function mapIPv4To6to4(ip: string): string {
+  const [address, suffix] = splitCIDR(ip);
+  const octets = address.split(".").map(Number);
+  const first = ((octets[0] << 8) | octets[1]).toString(16);
+  const second = ((octets[2] << 8) | octets[3]).toString(16);
+  return `2002:${first}:${second}::/${suffix + 16}`;
+}
diff --git a/library/helpers/mapIPv4WithIPv6Prefix.test.ts b/library/helpers/mapIPv4WithIPv6Prefix.test.ts
new file mode 100644
index 000000000..6f32dcaec
--- /dev/null
+++ b/library/helpers/mapIPv4WithIPv6Prefix.test.ts
@@ -0,0 +1,21 @@
+import * as t from "tap";
+import { mapIPv4WithIPv6Prefix } from "./mapIPv4WithIPv6Prefix";
+
+t.test("it embeds a single IPv4 address behind a prefix", async (t) => {
+  t.equal(
+    mapIPv4WithIPv6Prefix("127.0.0.1", "64:ff9b::", 96),
+    "64:ff9b::127.0.0.1/128"
+  );
+  t.equal(mapIPv4WithIPv6Prefix("10.0.0.1", "::", 96), "::10.0.0.1/128");
+});
+
+t.test("it adjusts the prefix length for an IPv4 CIDR range", async (t) => {
+  t.equal(
+    mapIPv4WithIPv6Prefix("10.0.0.0/8", "64:ff9b::", 96),
+    "64:ff9b::10.0.0.0/104"
+  );
+  t.equal(
+    mapIPv4WithIPv6Prefix("192.168.0.0/16", "64:ff9b:1::", 96),
+    "64:ff9b:1::192.168.0.0/112"
+  );
+});
diff --git a/library/helpers/mapIPv4WithIPv6Prefix.ts b/library/helpers/mapIPv4WithIPv6Prefix.ts
new file mode 100644
index 000000000..98de8dc56
--- /dev/null
+++ b/library/helpers/mapIPv4WithIPv6Prefix.ts
@@ -0,0 +1,15 @@
+import { splitCIDR } from "./splitCIDR";
+
+/**
+ * Embeds an IPv4 address as the trailing bits of a fixed-length IPv6 prefix.
+ * Used for transition mechanisms that place the IPv4 address at the end of the
+ * address, e.g. NAT64 (64:ff9b::/96) and IPv4-compatible addresses (::/96).
+ */
+export function mapIPv4WithIPv6Prefix(
+  ip: string,
+  prefix: string,
+  prefixBitLength: number
+): string {
+  const [address, suffix] = splitCIDR(ip);
+  return `${prefix}${address}/${suffix + prefixBitLength}`;
+}
diff --git a/library/helpers/splitCIDR.test.ts b/library/helpers/splitCIDR.test.ts
new file mode 100644
index 000000000..5eff47b5f
--- /dev/null
+++ b/library/helpers/splitCIDR.test.ts
@@ -0,0 +1,23 @@
+import * as t from "tap";
+import { splitCIDR } from "./splitCIDR";
+
+t.test("it splits an IP with a CIDR suffix", async (t) => {
+  t.same(splitCIDR("10.0.0.0/8"), ["10.0.0.0", 8]);
+  t.same(splitCIDR("192.168.0.0/16"), ["192.168.0.0", 16]);
+  t.same(splitCIDR("2001:db8::/32"), ["2001:db8::", 32]);
+});
+
+t.test(
+  "it defaults to a single-host prefix when no suffix is present",
+  async (t) => {
+    t.same(splitCIDR("127.0.0.1"), ["127.0.0.1", 32]);
+    t.same(splitCIDR("::1"), ["::1", 128]);
+  }
+);
+
+t.test("it handles boundary suffix values", async (t) => {
+  t.same(splitCIDR("0.0.0.0/0"), ["0.0.0.0", 0]);
+  t.same(splitCIDR("::/0"), ["::", 0]);
+  t.same(splitCIDR("127.0.0.1/32"), ["127.0.0.1", 32]);
+  t.same(splitCIDR("::1/128"), ["::1", 128]);
+});
diff --git a/library/helpers/splitCIDR.ts b/library/helpers/splitCIDR.ts
new file mode 100644
index 000000000..52ee499a5
--- /dev/null
+++ b/library/helpers/splitCIDR.ts
@@ -0,0 +1,12 @@
+/**
+ * Splits an IP address into its address part and prefix length.
+ * e.g. "10.0.0.0/8" -> ["10.0.0.0", 8], "127.0.0.1" -> ["127.0.0.1", 32]
+ * e.g. "::1" -> ["::1", 128]
+ */
+export function splitCIDR(ip: string): [string, number] {
+  if (!ip.includes("/")) {
+    return [ip, ip.includes(":") ? 128 : 32];
+  }
+  const [address, suffix] = ip.split("/");
+  return [address, Number.parseInt(suffix, 10)];
+}
diff --git a/library/vulnerabilities/ssrf/containsPrivateIPAddress.test.ts b/library/vulnerabilities/ssrf/containsPrivateIPAddress.test.ts
index b224dfdf1..b787367ad 100644
--- a/library/vulnerabilities/ssrf/containsPrivateIPAddress.test.ts
+++ b/library/vulnerabilities/ssrf/containsPrivateIPAddress.test.ts
@@ -34,6 +34,14 @@ const publicIPs = [
   "::ffff:1.2.3.4",
   "::ffff:172.1.2.3",
   "::ffff:192.145.0.0",
+  "64:ff9b::8.8.8.8",
+  "64:ff9b:1::8.8.8.8",
+  "2002:808:808::",
+  "::8.8.8.8",
+
+  // NAT64-encoded addresses just outside the 10.0.0.0/8 private range
+  "64:ff9b::9ff:ffff", // 9.255.255.255
+  "64:ff9b::b00:0", // 11.0.0.0
 ];
 
 const privateIPs = [
@@ -163,6 +171,32 @@ const privateIPs = [
 
   // Alibaba Cloud metadata service
   "100.100.100.200",
+
+  // NAT64 (RFC 6052) encoding private IPv4 addresses
+  "64:ff9b::7f00:1", // 127.0.0.1
+  "64:ff9b::a00:0", // 10.0.0.0 (start of 10.0.0.0/8)
+  "64:ff9b::a00:1", // 10.0.0.1
+  "64:ff9b::a00:203", // 10.0.2.3 (inside 10.0.0.0/8, not the network address)
+  "64:ff9b::c0a8:1", // 192.168.0.1
+  "64:ff9b::a9fe:a9fe", // 169.254.169.254 (cloud metadata)
+
+  // NAT64 Local-Use prefix (RFC 8215) encoding private IPv4 addresses
+  "64:ff9b:1::7f00:1", // 127.0.0.1
+  "64:ff9b:1::a00:1", // 10.0.0.1
+  "64:ff9b:1::c0a8:1", // 192.168.0.1
+  "64:ff9b:1::a9fe:a9fe", // 169.254.169.254 (cloud metadata)
+
+  // 6to4 (RFC 3056) encoding private IPv4 addresses
+  "2002:7f00:1::", // 127.0.0.1
+  "2002:a00:1::", // 10.0.0.1
+  "2002:c0a8:1::", // 192.168.0.1
+  "2002:a9fe:a9fe::", // 169.254.169.254 (cloud metadata)
+
+  // IPv4-compatible IPv6 addresses (RFC 4291) encoding private IPv4 addresses
+  "::7f00:1", // 127.0.0.1
+  "::a00:1", // 10.0.0.1
+  "::c0a8:1", // 192.168.0.1
+  "::a9fe:a9fe", // 169.254.169.254 (cloud metadata)
 ];
 
 const invalidIPs = [
diff --git a/library/vulnerabilities/ssrf/isPrivateIP.ts b/library/vulnerabilities/ssrf/isPrivateIP.ts
index d5f756e4a..24e126168 100644
--- a/library/vulnerabilities/ssrf/isPrivateIP.ts
+++ b/library/vulnerabilities/ssrf/isPrivateIP.ts
@@ -1,4 +1,5 @@
 import { addIPv4MappedAddresses } from "../../helpers/addIPv4MappedAddresses";
+import { addIPv4TransitionAddresses } from "../../helpers/addIPv4TransitionAddresses";
 import { IPMatcher } from "../../helpers/ip-matcher/IPMatcher";
 
 const PRIVATE_IP_RANGES = [
@@ -36,6 +37,7 @@ const PRIVATE_IPV6_RANGES = [
 // Small list, frequently accessed: add IPv4-mapped versions at creation time for fast lookups
 const privateIp = new IPMatcher([
   ...addIPv4MappedAddresses(PRIVATE_IP_RANGES),
+  ...addIPv4TransitionAddresses(PRIVATE_IP_RANGES),
   ...PRIVATE_IPV6_RANGES,
 ]);