diff --git a/Cargo.lock b/Cargo.lock
index db75d907..1541ee69 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1237,7 +1237,7 @@ dependencies = [
  "prost-types 0.14.4",
  "protoc-bin-vendored",
  "quickcheck",
- "rand 0.9.4",
+ "rand 0.8.7",
  "rand_chacha 0.9.0",
  "rocksdb",
  "rstest",
@@ -1282,7 +1282,7 @@ name = "dsm-sphincs"
 version = "0.1.0"
 dependencies = [
  "blake3",
- "rand 0.9.4",
+ "rand 0.8.7",
  "rand_chacha 0.9.0",
  "subtle",
  "zeroize",
@@ -1342,7 +1342,7 @@ dependencies = [
  "prost-types 0.14.4",
  "protoc-bin-vendored",
  "quickcheck",
- "rand 0.9.4",
+ "rand 0.8.7",
  "rand_chacha 0.9.0",
  "rcgen",
  "reqwest",
@@ -1393,7 +1393,7 @@ dependencies = [
  "ml-kem",
  "once_cell",
  "prost 0.14.4",
- "rand 0.8.6",
+ "rand 0.8.7",
  "reqwest",
  "rusqlite",
  "rustls",
@@ -1445,7 +1445,7 @@ dependencies = [
  "dsm",
  "instant",
  "prost 0.14.4",
- "rand 0.9.4",
+ "rand 0.8.7",
  "rand_chacha 0.9.0",
  "regex",
  "reqwest",
@@ -3547,9 +3547,9 @@ checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09"
 
 [[package]]
 name = "rand"
-version = "0.8.6"
+version = "0.8.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
+checksum = "22f6172bdec972074665ed81ed53b71da00bfc44b65a753cfde883ec4c702a1a"
 dependencies = [
  "libc",
  "rand_chacha 0.3.1",
diff --git a/crates/dsm-sphincs/Cargo.toml b/crates/dsm-sphincs/Cargo.toml
index 85796d42..014cbdcc 100644
--- a/crates/dsm-sphincs/Cargo.toml
+++ b/crates/dsm-sphincs/Cargo.toml
@@ -14,5 +14,5 @@ blake3 = { version = "1", default-features = false }
 subtle = { version = "2", default-features = false }
 zeroize = { version = "1", default-features = false, features = ["derive", "alloc"] }
 # Deterministic keygen expands the 32-byte seed via ChaCha20 (no_std, no OS RNG).
-rand = { version = "0.9", default-features = false }
+rand = { version = "0.8", default-features = false }
 rand_chacha = { version = "0.9", default-features = false }
diff --git a/dsm_client/deterministic_state_machine/dsm/Cargo.toml b/dsm_client/deterministic_state_machine/dsm/Cargo.toml
index a62678e7..d9024e03 100644
--- a/dsm_client/deterministic_state_machine/dsm/Cargo.toml
+++ b/dsm_client/deterministic_state_machine/dsm/Cargo.toml
@@ -136,7 +136,7 @@ bitflags = "2.13.0"
 arrayref = "0.3.9"
 argon2 = "0.5.3"
 
-rand = "0.9.2"
+rand = "0.8.7"
 uuid = { version = "1.23", features = ["std"] }
 # serde_cbor removed from code paths (unmaintained); deterministic CBOR is hand-encoded locally
 # Prefer stable crypto crates to reduce duplicate dependency versions across workspace.
diff --git a/dsm_client/deterministic_state_machine/dsm_sdk/Cargo.toml b/dsm_client/deterministic_state_machine/dsm_sdk/Cargo.toml
index a7f7481c..5573fa3b 100644
--- a/dsm_client/deterministic_state_machine/dsm_sdk/Cargo.toml
+++ b/dsm_client/deterministic_state_machine/dsm_sdk/Cargo.toml
@@ -114,7 +114,7 @@ ed25519-dalek = { version = "2", default-features = false, features = ["std"] }
 # AEAD
 chacha20poly1305 = { version = "0.10", default-features = false, features = ["alloc", "std"] }
 hmac = "0.13.0"
-rand = "0.9.2"
+rand = "0.8.7"
 rand_chacha = "0.9.0"
 getrandom = "0.4.2"
 merlin = "3.0.0"
diff --git a/tools/vertical_validation/Cargo.toml b/tools/vertical_validation/Cargo.toml
index 96d6b358..2723de36 100644
--- a/tools/vertical_validation/Cargo.toml
+++ b/tools/vertical_validation/Cargo.toml
@@ -43,7 +43,7 @@ instant = "0.1"
 dsm = { version = "0.1.0-beta.3", path = "../../dsm_client/deterministic_state_machine/dsm" }
 
 # Deterministic seeded RNG for reproducible property tests
-rand = "0.9.2"
+rand = "0.8.7"
 rand_chacha = "0.9.0"
 
 [lints]