diff --git a/Cargo.lock b/Cargo.lock
index cabd48eba3..10126eeb49 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -394,12 +394,6 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"
 
-[[package]]
-name = "base64"
-version = "0.13.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e1b586273c5702936fe7b7d6896644d8be71e6314cfe09d3167c95f712589e8"
-
 [[package]]
 name = "base64"
 version = "0.21.5"
@@ -1914,7 +1908,7 @@ source = "git+https://github.com/oxidecomputer/dropshot?branch=main#ff87a0175a6c
 dependencies = [
  "async-stream",
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "bytes",
  "camino",
  "chrono",
@@ -2092,7 +2086,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "chrono",
  "http",
  "omicron-sled-agent",
@@ -2506,7 +2500,7 @@ dependencies = [
 name = "gateway-client"
 version = "0.1.0"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "chrono",
  "gateway-messages",
  "omicron-workspace-hack",
@@ -2734,7 +2728,7 @@ version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06683b93020a07e3dbcf5f8c0f6d40080d725bea7936fc01ad345c01b97dc270"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "bytes",
  "headers-core",
  "http",
@@ -4061,7 +4055,7 @@ dependencies = [
  "async-bb8-diesel",
  "async-trait",
  "authz-macros",
- "base64 0.21.5",
+ "base64",
  "bb8",
  "camino",
  "camino-tempfile",
@@ -4142,7 +4136,7 @@ name = "nexus-inventory"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "base64 0.21.5",
+ "base64",
  "chrono",
  "expectorate",
  "gateway-client",
@@ -4222,7 +4216,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "api_identity",
- "base64 0.21.5",
+ "base64",
  "chrono",
  "dns-service-client",
  "futures",
@@ -4602,7 +4596,7 @@ name = "omicron-gateway"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "base64 0.21.5",
+ "base64",
  "clap 4.4.3",
  "dropshot",
  "expectorate",
@@ -4646,7 +4640,7 @@ dependencies = [
  "assert_matches",
  "async-bb8-diesel",
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "buf-list",
  "camino",
  "cancel-safe-futures",
@@ -4856,7 +4850,7 @@ dependencies = [
  "anyhow",
  "assert_matches",
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "bootstore",
  "bootstrap-agent-client",
  "bytes",
@@ -5275,7 +5269,7 @@ name = "oxide-client"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "base64 0.21.5",
+ "base64",
  "chrono",
  "futures",
  "http",
@@ -5667,7 +5661,7 @@ version = "3.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3163d2912b7c3b52d651a055f2c7eec9ba5cd22d26ef75b8dd3a59980b185923"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "serde",
 ]
 
@@ -5924,7 +5918,7 @@ version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49b6c5ef183cd3ab4ba005f1ca64c21e8bd97ce4699cfea9e8d9a2c4958ca520"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "byteorder",
  "bytes",
  "fallible-iterator",
@@ -6170,7 +6164,7 @@ version = "0.1.0"
 source = "git+https://github.com/oxidecomputer/propolis?rev=3e1d129151c3621d28ead5c6e5760693ba6e7fec#3e1d129151c3621d28ead5c6e5760693ba6e7fec"
 dependencies = [
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "futures",
  "progenitor",
  "rand 0.8.5",
@@ -6192,7 +6186,7 @@ source = "git+https://github.com/oxidecomputer/propolis?rev=3e1d129151c3621d28ea
 dependencies = [
  "anyhow",
  "atty",
- "base64 0.21.5",
+ "base64",
  "clap 4.4.3",
  "dropshot",
  "futures",
@@ -6624,7 +6618,7 @@ version = "0.11.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "046cd98826c46c2ac8ddecae268eb5c2e58628688a5fc7a2643704a73faba95b"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "bytes",
  "encoding_rs",
  "futures-core",
@@ -6718,7 +6712,7 @@ version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b91f7eff05f748767f183df4320a63d6936e9c6107d97c9e6bdd9784f4289c94"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "bitflags 2.4.0",
  "serde",
  "serde_derive",
@@ -6887,7 +6881,7 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a5885493fdf0be6cdff808d1533ce878d21cfa49c7086fa00c66355cd9141bfc"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "blake2b_simd",
  "constant_time_eq 0.3.0",
  "crossbeam-utils",
@@ -6993,7 +6987,7 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2d3987094b1d07b653b7dfdc3f70ce9a1da9c51ac18c1b06b662e4f9a0e9f4b2"
 dependencies = [
- "base64 0.21.5",
+ "base64",
 ]
 
 [[package]]
@@ -7064,7 +7058,7 @@ name = "samael"
 version = "0.0.10"
 source = "git+https://github.com/njaremko/samael?branch=master#52028e45d11ceb7114bf0c730a9971207e965602"
 dependencies = [
- "base64 0.21.5",
+ "base64",
  "bindgen",
  "chrono",
  "data-encoding",
@@ -7390,14 +7384,15 @@ dependencies = [
 
 [[package]]
 name = "serde_with"
-version = "2.3.3"
+version = "3.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07ff71d2c147a7b57362cead5e22f772cd52f6ab31cfcd9edcd7f6aeb2a0afbe"
+checksum = "64cd236ccc1b7a29e7e2739f27c0b2dd199804abc4290e32f59f3b68d6405c23"
 dependencies = [
- "base64 0.13.1",
+ "base64",
  "chrono",
  "hex",
  "indexmap 1.9.3",
+ "indexmap 2.1.0",
  "serde",
  "serde_json",
  "serde_with_macros",
@@ -7406,9 +7401,9 @@ dependencies = [
 
 [[package]]
 name = "serde_with_macros"
-version = "2.3.3"
+version = "3.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "881b6f881b17d13214e5d494c939ebab463d01264ce1811e9d4ac3a882e7695f"
+checksum = "93634eb5f75a2323b16de4748022ac4297f9e76b6dced2be287a099f41b5e788"
 dependencies = [
  "darling 0.20.3",
  "proc-macro2",
@@ -9593,7 +9588,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "async-trait",
- "base64 0.21.5",
+ "base64",
  "bootstrap-agent-client",
  "buf-list",
  "bytes",
diff --git a/Cargo.toml b/Cargo.toml
index 98c83eb6e7..4da39b7902 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -321,7 +321,7 @@ serde_json = "1.0.108"
 serde_path_to_error = "0.1.14"
 serde_tokenstream = "0.2"
 serde_urlencoded = "0.7.1"
-serde_with = "2.3.3"
+serde_with = "3.4.0"
 serial_test = "0.10"
 sha2 = "0.10.8"
 sha3 = "0.10.8"