diff --git a/README.md b/README.md
index 022b149..54daf87 100644
--- a/README.md
+++ b/README.md
@@ -58,7 +58,7 @@ Download the binaries from the most recent release assets on Github.
 
 ### Build from sources
 
-- A recent version of **Go** (1.21+) should be installed. [Go installation](https://go.dev/doc/install)
+- A recent version of **Go** (1.20+) should be installed. [Go installation](https://go.dev/doc/install)
 
 - Clone the repository `git clone https://github.com/csaf-poc/csaf_distribution.git `
 
diff --git a/cmd/csaf_downloader/config.go b/cmd/csaf_downloader/config.go
index 1761d75..367780f 100644
--- a/cmd/csaf_downloader/config.go
+++ b/cmd/csaf_downloader/config.go
@@ -13,12 +13,13 @@ import (
 	"fmt"
 	"io"
 	"log"
-	"log/slog"
 	"net/http"
 	"os"
 	"path/filepath"
 	"time"
 
+	"golang.org/x/exp/slog"
+
 	"github.com/csaf-poc/csaf_distribution/v3/internal/certs"
 	"github.com/csaf-poc/csaf_distribution/v3/internal/filter"
 	"github.com/csaf-poc/csaf_distribution/v3/internal/models"
diff --git a/cmd/csaf_downloader/downloader.go b/cmd/csaf_downloader/downloader.go
index 1799a84..7fa0c7c 100644
--- a/cmd/csaf_downloader/downloader.go
+++ b/cmd/csaf_downloader/downloader.go
@@ -19,7 +19,6 @@ import (
 	"fmt"
 	"hash"
 	"io"
-	"log/slog"
 	"net/http"
 	"net/url"
 	"os"
@@ -30,6 +29,8 @@ import (
 	"sync"
 	"time"
 
+	"golang.org/x/exp/slog"
+
 	"github.com/ProtonMail/gopenpgp/v2/crypto"
 	"golang.org/x/time/rate"
 
diff --git a/cmd/csaf_downloader/forwarder.go b/cmd/csaf_downloader/forwarder.go
index 8ceb0e5..eda6595 100644
--- a/cmd/csaf_downloader/forwarder.go
+++ b/cmd/csaf_downloader/forwarder.go
@@ -12,13 +12,14 @@ import (
 	"bytes"
 	"crypto/tls"
 	"io"
-	"log/slog"
 	"mime/multipart"
 	"net/http"
 	"os"
 	"path/filepath"
 	"strings"
 
+	"golang.org/x/exp/slog"
+
 	"github.com/csaf-poc/csaf_distribution/v3/internal/misc"
 	"github.com/csaf-poc/csaf_distribution/v3/util"
 )
@@ -57,7 +58,10 @@ type forwarder struct {
 
 // newForwarder creates a new forwarder.
 func newForwarder(cfg *config) *forwarder {
-	queue := max(1, cfg.ForwardQueue)
+	queue := cfg.ForwardQueue
+	if queue < 1 {
+		queue = 1
+	}
 	return &forwarder{
 		cfg:  cfg,
 		cmds: make(chan func(*forwarder), queue),
diff --git a/cmd/csaf_downloader/forwarder_test.go b/cmd/csaf_downloader/forwarder_test.go
index c7f8634..dc515ad 100644
--- a/cmd/csaf_downloader/forwarder_test.go
+++ b/cmd/csaf_downloader/forwarder_test.go
@@ -14,7 +14,6 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
-	"log/slog"
 	"mime"
 	"mime/multipart"
 	"net/http"
@@ -23,6 +22,8 @@ import (
 	"strings"
 	"testing"
 
+	"golang.org/x/exp/slog"
+
 	"github.com/csaf-poc/csaf_distribution/v3/internal/options"
 	"github.com/csaf-poc/csaf_distribution/v3/util"
 )
diff --git a/cmd/csaf_downloader/main.go b/cmd/csaf_downloader/main.go
index 7c0e564..daff163 100644
--- a/cmd/csaf_downloader/main.go
+++ b/cmd/csaf_downloader/main.go
@@ -11,10 +11,11 @@ package main
 
 import (
 	"context"
-	"log/slog"
 	"os"
 	"os/signal"
 
+	"golang.org/x/exp/slog"
+
 	"github.com/csaf-poc/csaf_distribution/v3/internal/options"
 )
 
diff --git a/cmd/csaf_downloader/stats.go b/cmd/csaf_downloader/stats.go
index 6bafbf7..237420a 100644
--- a/cmd/csaf_downloader/stats.go
+++ b/cmd/csaf_downloader/stats.go
@@ -8,7 +8,7 @@
 
 package main
 
-import "log/slog"
+import "golang.org/x/exp/slog"
 
 // stats contains counters of the downloads.
 type stats struct {
diff --git a/cmd/csaf_downloader/stats_test.go b/cmd/csaf_downloader/stats_test.go
index 69567ab..b3ab914 100644
--- a/cmd/csaf_downloader/stats_test.go
+++ b/cmd/csaf_downloader/stats_test.go
@@ -11,8 +11,9 @@ package main
 import (
 	"bytes"
 	"encoding/json"
-	"log/slog"
 	"testing"
+
+	"golang.org/x/exp/slog"
 )
 
 func TestStatsAdd(t *testing.T) {
diff --git a/docs/Development.md b/docs/Development.md
index 0a7004a..218cb7e 100644
--- a/docs/Development.md
+++ b/docs/Development.md
@@ -1,5 +1,10 @@
 # Development
 
+## Supported Go versions
+
+We support the latest version and the one before
+the latest version of Go (currently 1.21 and 1.20).
+
 ## Generated files
 
 Some source code files are machine generated. At the moment these are only
diff --git a/examples/purls_searcher/main.go b/examples/purls_searcher/main.go
index b01e671..a91470b 100644
--- a/examples/purls_searcher/main.go
+++ b/examples/purls_searcher/main.go
@@ -7,9 +7,10 @@ import (
 	"fmt"
 	"log"
 	"os"
-	"slices"
 	"strings"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/csaf-poc/csaf_distribution/v3/csaf"
 )
 
@@ -70,7 +71,9 @@ func newURLFinder(ids []string) *urlFinder {
 
 // clear resets the url finder after a run on an advisory.
 func (uf *urlFinder) clear() {
-	clear(uf.urls)
+	for i := range uf.urls {
+		uf.urls[i] = uf.urls[i][:0]
+	}
 }
 
 // dumpURLs dumps the found URLs to stdout.
diff --git a/go.mod b/go.mod
index 82a20c5..469c8a3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/csaf-poc/csaf_distribution/v3
 
-go 1.21
+go 1.20
 
 require (
 	github.com/BurntSushi/toml v1.3.2
@@ -14,6 +14,7 @@ require (
 	github.com/santhosh-tekuri/jsonschema/v5 v5.3.1
 	go.etcd.io/bbolt v1.3.8
 	golang.org/x/crypto v0.14.0
+	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa
 	golang.org/x/term v0.13.0
 	golang.org/x/time v0.3.0
 )
@@ -26,6 +27,6 @@ require (
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/shopspring/decimal v1.3.1 // indirect
 	golang.org/x/net v0.17.0 // indirect
-	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/sys v0.14.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
 )
diff --git a/go.sum b/go.sum
index c2643b9..3a101d4 100644
--- a/go.sum
+++ b/go.sum
@@ -9,8 +9,6 @@ github.com/ProtonMail/go-crypto v0.0.0-20230923063757-afb1ddc0824c h1:kMFnB0vCcX
 github.com/ProtonMail/go-crypto v0.0.0-20230923063757-afb1ddc0824c/go.mod h1:EjAoLdwvbIOoOQr3ihjnSoLZRtE8azugULFRteWMNc0=
 github.com/ProtonMail/go-mime v0.0.0-20230322103455-7d82a3887f2f h1:tCbYj7/299ekTTXpdwKYF8eBlsYsDVoggDAuAjoK66k=
 github.com/ProtonMail/go-mime v0.0.0-20230322103455-7d82a3887f2f/go.mod h1:gcr0kNtGBqin9zDW9GOHcVntrwnjrK+qdJ06mWYBybw=
-github.com/ProtonMail/gopenpgp/v2 v2.7.3 h1:AJu1OI/1UWVYZl6QcCLKGu9OTngS2r52618uGlje84I=
-github.com/ProtonMail/gopenpgp/v2 v2.7.3/go.mod h1:IhkNEDaxec6NyzSI0PlxapinnwPVIESk8/76da3Ct3g=
 github.com/ProtonMail/gopenpgp/v2 v2.7.4 h1:Vz/8+HViFFnf2A6XX8JOvZMrA6F5puwNvvF21O1mRlo=
 github.com/ProtonMail/gopenpgp/v2 v2.7.4/go.mod h1:IhkNEDaxec6NyzSI0PlxapinnwPVIESk8/76da3Ct3g=
 github.com/PuerkitoBio/goquery v1.8.1 h1:uQxhNlArOIdbrH1tr0UXwdVFgDcZDrZVdcpygAcwmWM=
@@ -19,7 +17,6 @@ github.com/andybalholm/cascadia v1.3.1/go.mod h1:R4bJ1UQfqADjvDa4P6HZHLh/3OxWWEq
 github.com/andybalholm/cascadia v1.3.2 h1:3Xi6Dw5lHF15JtdcmAHD3i1+T8plmv7BQ/nsViSLyss=
 github.com/andybalholm/cascadia v1.3.2/go.mod h1:7gtRlve5FxPPgIgX36uWBX58OdBsSS6lUvCFb+h7KvU=
 github.com/bwesterb/go-ristretto v1.2.3/go.mod h1:fUIoIZaG73pV5biE2Blr2xEzDoMj7NFEuV9ekS419A0=
-github.com/cloudflare/circl v1.3.3 h1:fE/Qz0QdIGqeWfnwq0RE0R7MI51s0M2E4Ga9kq5AEMs=
 github.com/cloudflare/circl v1.3.3/go.mod h1:5XYMA4rFBvNIrhs50XuiBJ15vF2pZn4nnUKZrLbUZFA=
 github.com/cloudflare/circl v1.3.6 h1:/xbKIqSHbZXHwkhbrhrt2YOHIwYJlXH94E3tI/gDlUg=
 github.com/cloudflare/circl v1.3.6/go.mod h1:5XYMA4rFBvNIrhs50XuiBJ15vF2pZn4nnUKZrLbUZFA=
@@ -28,6 +25,7 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
 github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/jessevdk/go-flags v1.5.0 h1:1jKYvbxEjfUl0fmqTCOfonvskHHXMjBySTLW4y9LFvc=
 github.com/jessevdk/go-flags v1.5.0/go.mod h1:Fw0T6WPc1dYxT4mKEZRfG5kJhaTDP9pj1c2EWnYs/m4=
@@ -44,20 +42,17 @@ github.com/shopspring/decimal v1.3.1/go.mod h1:DKyhrW/HYNuLGql+MJL6WCR6knT2jwCFR
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
-github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
-go.etcd.io/bbolt v1.3.7 h1:j+zJOnnEjF/kyHlDDgGnVL/AIqIJPq8UoB2GSNfkUfQ=
-go.etcd.io/bbolt v1.3.7/go.mod h1:N9Mkw9X8x5fupy0IKsmuqVtoGDyxsaDlbk4Rd05IAQw=
 go.etcd.io/bbolt v1.3.8 h1:xs88BrvEv273UsB79e0hcVrlUWmS0a8upikMFhSyAtA=
 go.etcd.io/bbolt v1.3.8/go.mod h1:N9Mkw9X8x5fupy0IKsmuqVtoGDyxsaDlbk4Rd05IAQw=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.3.1-0.20221117191849-2c476679df9a/go.mod h1:hebNnKkNXi2UzZN1eVRvBB7co0a+JxK6XbPiWVs/3J4=
 golang.org/x/crypto v0.7.0/go.mod h1:pYwdfH91IfpZVANVyUOhSIPZaFoJGxTFbZhFTx+dXZU=
-golang.org/x/crypto v0.13.0 h1:mvySKfSWJ+UKUii46M40LOvyWfN0s2U+46/jDd0e6Ck=
-golang.org/x/crypto v0.13.0/go.mod h1:y6Z2r+Rw4iayiXXAIxJIDAJ1zMW4yaTpebo8fPOliYc=
 golang.org/x/crypto v0.14.0 h1:wBqGXzWJW6m1XrIKlAH0Hs1JJ7+9KBwnIO8v66Q9cHc=
 golang.org/x/crypto v0.14.0/go.mod h1:MVFd36DqK4CsrnJYDkBA3VC4m2GkXAM0PvzMCn4JQf4=
+golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa h1:FRnLl4eNAQl8hwxVVC17teOw8kdjVDVAiFMtgUdTSRQ=
+golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa/go.mod h1:zk2irFbV9DP96SEBUUAy67IdHUaZuSnrz1n472HUCLE=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -69,8 +64,6 @@ golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.7.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.8.0/go.mod h1:QVkue5JL9kW//ek3r6jTKnTFis1tRmNAW2P1shuFdJc=
 golang.org/x/net v0.9.0/go.mod h1:d48xBJpPfHeWQsugry2m+kC02ZBRGRgulfHnEXEuWns=
-golang.org/x/net v0.15.0 h1:ugBLEUaxABaB5AJqW9enI0ACdci2RUd4eP51NTBvuJ8=
-golang.org/x/net v0.15.0/go.mod h1:idbUs1IY1+zTqbi8yxTbhexhEEk5ur9LInksu6HrEpk=
 golang.org/x/net v0.17.0 h1:pVaXccu2ozPjCXewfr1S7xza/zcXTity9cCdXQYSjIM=
 golang.org/x/net v0.17.0/go.mod h1:NxSsAGuq816PNPmqtQdLE42eU2Fs7NoRIZrHJAlaCOE=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -88,18 +81,14 @@ golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.7.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.12.0 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
-golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
-golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
+golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
 golang.org/x/term v0.6.0/go.mod h1:m6U89DPEgQRMq3DNkDClhWw02AUbt2daBVO4cn4Hv9U=
 golang.org/x/term v0.7.0/go.mod h1:P32HKFT3hSsZrRxla30E9HqToFYAQPCMs/zFMBUFqPY=
-golang.org/x/term v0.12.0 h1:/ZfYdc3zq+q02Rv9vGqTeSItdzZTSNDmfTi0mBAuidU=
-golang.org/x/term v0.12.0/go.mod h1:owVbMEjm3cBLCHdkQu9b1opXd4ETQWc3BhuQGKgXgvU=
 golang.org/x/term v0.13.0 h1:bb+I9cTfFazGW51MZqBVmZy7+JEJMouUHTUSKVQLBek=
 golang.org/x/term v0.13.0/go.mod h1:LTmsnFJwVN6bCy1rVCoS+qHT1HhALEFxKncY3WNNh4U=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/internal/options/log.go b/internal/options/log.go
index c8e828d..226072e 100644
--- a/internal/options/log.go
+++ b/internal/options/log.go
@@ -9,8 +9,9 @@
 package options
 
 import (
-	"log/slog"
 	"strings"
+
+	"golang.org/x/exp/slog"
 )
 
 // LogLevel implements a helper type to be used in configurations.
diff --git a/internal/options/log_test.go b/internal/options/log_test.go
index 6c93865..2272f0f 100644
--- a/internal/options/log_test.go
+++ b/internal/options/log_test.go
@@ -9,8 +9,9 @@
 package options
 
 import (
-	"log/slog"
 	"testing"
+
+	"golang.org/x/exp/slog"
 )
 
 func TestMarshalFlag(t *testing.T) {