src/go.mod                |  2 +-
 src/go.sum                |  4 ++--
 src/net/http/h2_bundle.go | 10 +++++++++-
 src/vendor/modules.txt    |  2 +-

diff --git a/src/go.mod b/src/go.mod
index 1040d0506f4f6ea8edc49fb2382912d6d0ba69d6..977370d2653873a561150e559bfab3bd7146e204 100644
--- a/src/go.mod
+++ b/src/go.mod
@@ -4,7 +4,7 @@ go 1.16
 
 require (
 	golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897
-	golang.org/x/net v0.0.0-20211201233224-64539c132272
+	golang.org/x/net v0.0.0-20211209100217-a5309b321dca
 	golang.org/x/sys v0.0.0-20201204225414-ed752295db88 // indirect
 	golang.org/x/text v0.3.4 // indirect
 )
diff --git a/src/go.sum b/src/go.sum
index 6e22abb20a275826dea05a3128b7fa08ad31b347..1032a505181ba734d8d765ef00f5688ec649daac 100644
--- a/src/go.sum
+++ b/src/go.sum
@@ -2,8 +2,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897 h1:pLI5jrR7OSLijeIDcmRxNmw2api+jEfxLoykJVice/E=
 golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20211201233224-64539c132272 h1:yz7zX5EMX9IFSUDQtHpohPOP+fh7w1Me4FH/El1jctU=
-golang.org/x/net v0.0.0-20211201233224-64539c132272/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20211209100217-a5309b321dca h1:UmeWAm8AwB6NA/e4FSaGlK1EKTLXKX3utx4Si+6kfPg=
+golang.org/x/net v0.0.0-20211209100217-a5309b321dca/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
diff --git a/src/net/http/h2_bundle.go b/src/net/http/h2_bundle.go
index 735f1b5eac604bc854dc64043628047696b0b51b..6a0c1acf5f6cfc47ed11da7a8e3876ee33c68c11 100644
--- a/src/net/http/h2_bundle.go
+++ b/src/net/http/h2_bundle.go
@@ -4373,7 +4373,15 @@ 	if sc.canonHeader == nil {
 		sc.canonHeader = make(map[string]string)
 	}
 	cv = CanonicalHeaderKey(v)
-	sc.canonHeader[v] = cv
+	// maxCachedCanonicalHeaders is an arbitrarily-chosen limit on the number of
+	// entries in the canonHeader cache. This should be larger than the number
+	// of unique, uncommon header keys likely to be sent by the peer, while not
+	// so high as to permit unreaasonable memory usage if the peer sends an unbounded
+	// number of unique header keys.
+	const maxCachedCanonicalHeaders = 32
+	if len(sc.canonHeader) < maxCachedCanonicalHeaders {
+		sc.canonHeader[v] = cv
+	}
 	return cv
 }
 
diff --git a/src/vendor/modules.txt b/src/vendor/modules.txt
index 652d4d07d24571b7833e527d67bfc31e68b46e7f..a37d539508c74592ed298db7a8f1a4be630aebb6 100644
--- a/src/vendor/modules.txt
+++ b/src/vendor/modules.txt
@@ -8,7 +8,7 @@ golang.org/x/crypto/curve25519
 golang.org/x/crypto/hkdf
 golang.org/x/crypto/internal/subtle
 golang.org/x/crypto/poly1305
-# golang.org/x/net v0.0.0-20211201233224-64539c132272
+# golang.org/x/net v0.0.0-20211209100217-a5309b321dca
 ## explicit
 golang.org/x/net/dns/dnsmessage
 golang.org/x/net/http/httpguts