diff --git a/Cargo.lock b/Cargo.lock
index 0d586129333a..3627bfa38f39 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3560,11 +3560,12 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.117"
+version = "1.0.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "455182ea6142b14f93f4bc5320a2b31c1f266b66a4a5c858b013302a5d8cbfc3"
+checksum = "4ab380d7d9f22ef3f21ad3e6c1ebe8e4fc7a2000ccba2e4d71fc96f15b2cb609"
 dependencies = [
  "itoa",
+ "memchr",
  "ryu",
  "serde",
 ]
diff --git a/cargo-guppy/Cargo.toml b/cargo-guppy/Cargo.toml
index cb478fcf0706..6540febcf8a8 100644
--- a/cargo-guppy/Cargo.toml
+++ b/cargo-guppy/Cargo.toml
@@ -17,6 +17,6 @@ guppy-cmdlib = { path = "../guppy-cmdlib" }
 itertools = "0.12.1"
 pathdiff = { version = "0.2.1", features = ["camino"] }
 serde = { version = "1.0.204", features = ["derive"] }
-serde_json = "1.0.117"
+serde_json = "1.0.121"
 toml_edit = "0.17.1"
 guppy-workspace-hack.workspace = true
diff --git a/guppy-summaries/Cargo.toml b/guppy-summaries/Cargo.toml
index dc077cc77993..14f7228bab52 100644
--- a/guppy-summaries/Cargo.toml
+++ b/guppy-summaries/Cargo.toml
@@ -37,4 +37,4 @@ guppy-workspace-hack.workspace = true
 [dev-dependencies]
 indoc = "2.0.5"
 pretty_assertions = "1.4.0"
-serde_json = "1.0.117"
+serde_json = "1.0.121"
diff --git a/guppy/Cargo.toml b/guppy/Cargo.toml
index 73f6b60962f2..c3a250553acd 100644
--- a/guppy/Cargo.toml
+++ b/guppy/Cargo.toml
@@ -47,7 +47,7 @@ proptest-derive = { version = "0.4.0", optional = true }
 rayon = { version = "1.10.0", optional = true }
 semver = "1.0.23"
 serde = { version = "1.0.204", features = ["derive"] }
-serde_json = "1.0.117"
+serde_json = "1.0.121"
 smallvec = "1.13.2"
 static_assertions = "1.1.0"
 target-spec = { version = "3.2.0", path = "../target-spec" }
diff --git a/target-spec/Cargo.toml b/target-spec/Cargo.toml
index c00f92efcf90..f943d842ad92 100644
--- a/target-spec/Cargo.toml
+++ b/target-spec/Cargo.toml
@@ -23,7 +23,7 @@ maintenance = { status = "actively-developed" }
 cfg-expr = { version = "0.16.0", features = ["targets"] }
 proptest = { version = "1.4.0", optional = true }
 serde = { version = "1.0.204", optional = true, features = ["derive"] }
-serde_json = { version = "1.0.117", optional = true }
+serde_json = { version = "1.0.121", optional = true }
 target-lexicon = { version = "0.12.15", features = ["std"] }
 unicode-ident = "1.0.12"
 guppy-workspace-hack.workspace = true
diff --git a/workspace-hack/Cargo.toml b/workspace-hack/Cargo.toml
index 86535737d7b4..c4c95655050e 100644
--- a/workspace-hack/Cargo.toml
+++ b/workspace-hack/Cargo.toml
@@ -30,7 +30,7 @@ regex-automata = { version = "0.4.5", default-features = false, features = ["dfa
 regex-syntax = { version = "0.8.2" }
 semver = { version = "1.0.23", features = ["serde"] }
 serde = { version = "1.0.204", features = ["alloc", "derive"] }
-serde_json = { version = "1.0.117", features = ["unbounded_depth"] }
+serde_json = { version = "1.0.121", features = ["unbounded_depth"] }
 toml = { version = "0.5.11", features = ["preserve_order"] }
 
 [build-dependencies]
@@ -41,7 +41,6 @@ syn-f595c2ba2a3f28df = { package = "syn", version = "2.0.48", features = ["extra
 
 [target.x86_64-unknown-linux-gnu.dependencies]
 libc = { version = "0.2.155" }
-memchr = { version = "2.7.4", default-features = false, features = ["std"] }
 once_cell = { version = "1.19.0" }
 rustix = { version = "0.38.31", features = ["fs", "termios"] }
 
@@ -50,7 +49,6 @@ libc = { version = "0.2.155" }
 
 [target.x86_64-apple-darwin.dependencies]
 libc = { version = "0.2.155", features = ["extra_traits"] }
-memchr = { version = "2.7.4", default-features = false, features = ["std"] }
 once_cell = { version = "1.19.0" }
 rustix = { version = "0.38.31", features = ["fs", "termios"] }
 
@@ -59,7 +57,6 @@ libc = { version = "0.2.155", features = ["extra_traits"] }
 
 [target.aarch64-apple-darwin.dependencies]
 libc = { version = "0.2.155", features = ["extra_traits"] }
-memchr = { version = "2.7.4", default-features = false, features = ["std"] }
 once_cell = { version = "1.19.0" }
 rustix = { version = "0.38.31", features = ["fs", "termios"] }