CVE-2021-41173

Geth Node Vulnerable to DoS via maliciously crafted p2p message

func (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, newnode node, resolved int, err error) {
	// If we reached the requested path, return the current node
	if pos >= len(path) {
		// Although we most probably have the original node expanded, encoding
		// that into consensus form can be nasty (needs to cascade down) and
		// time consuming. Instead, just pull the hash up from disk directly.
		var hash hashNode
		if node, ok := origNode.(hashNode); ok {
			hash = node
		} else {
			hash, _ = origNode.cache()
		}

				// Storage slots requested, open the storage trie and retrieve from there
				account, err := snap.Account(common.BytesToHash(pathset[0]))
				loads++ // always account database reads, even for failures
				if account == nil {
					break
				}
				stTrie, err := trie.NewSecure(common.BytesToHash(account.Root), triedb)

A vulnerable node is susceptible to crash when processing a maliciously crafted message from a peer, via the snap/1 protocol. The crash can be triggered by sending a malicious snap/1 GetTrieNodes package.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2021-41173 has a CVSS score of 5.7 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.10.9); upgrading removes the vulnerable code path.

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--- a/eth/protocols/snap/handler.go
+++ b/eth/protocols/snap/handler.go
@@ -469,7 +469,7 @@ func handleMessage(backend Backend, peer *Peer) error {
 				// Storage slots requested, open the storage trie and retrieve from there
 				account, err := snap.Account(common.BytesToHash(pathset[0]))
 				loads++ // always account database reads, even for failures
-				if err != nil {
+				if err != nil || account == nil {
 					break
 				}
 				stTrie, err := trie.NewSecure(common.BytesToHash(account.Root), triedb)
diff --git a/trie/trie.go b/trie/trie.go
index 7ea7efa835..d0f0d4e2bc 100644
--- a/trie/trie.go
+++ b/trie/trie.go
@@ -174,6 +174,10 @@ func (t *Trie) TryGetNode(path []byte) ([]byte, int, error) {
 }
 
 func (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, newnode node, resolved int, err error) {
+	// If non-existent path requested, abort
+	if origNode == nil {
+		return nil, nil, 0, nil
+	}
 	// If we reached the requested path, return the current node
 	if pos >= len(path) {
 		// Although we most probably have the original node expanded, encoding
@@ -193,10 +197,6 @@ func (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, new
 	}
 	// Path still needs to be traversed, descend into children
 	switch n := (origNode).(type) {
-	case nil:
-		// Non-existent path requested, abort
-		return nil, nil, 0, nil
-
 	case valueNode:
 		// Path prematurely ended, abort
 		return nil, nil, 0, nil

The fixes were merged into #23657, with commit f1fd963, and released as part of Geth v1.10.9 on Sept 29, 2021.

1. What is CVE-2021-41173? CVE-2021-41173 is a medium-severity improper input validation vulnerability in github.com/ethereum/go-ethereum (go), affecting versions < 1.10.9. It is fixed in 1.10.9. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2021-41173? CVE-2021-41173 has a CVSS score of 5.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/ethereum/go-ethereum are affected by CVE-2021-41173? github.com/ethereum/go-ethereum (go) versions < 1.10.9 is affected.
4. Is there a fix for CVE-2021-41173? Yes. CVE-2021-41173 is fixed in 1.10.9. Upgrade to this version or later.
5. Is CVE-2021-41173 exploitable, and should I be worried? Whether CVE-2021-41173 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-41173 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-41173? Upgrade github.com/ethereum/go-ethereum to 1.10.9 or later.

Other vulnerabilities in github.com/ethereum/go-ethereum