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GHSA-xw37-57qp-9mm4

MediumCVSS 5.3 / 10
Published Jun 29, 2021·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

Impact

A consensus-vulnerability in Geth could cause a chain split, where vulnerable versions refuse to accept the canonical chain.

Description

A flaw was repoted at 2020-08-11 by John Youngseok Yang (Software Platform Lab), where a particular sequence of transactions could cause a consensus failure.

  • Tx 1:

    • sender invokes caller.
    • caller invokes 0xaa. 0xaa has 3 wei, does a self-destruct-to-self
    • caller does a 1 wei -call to 0xaa, who thereby has 1 wei (the code in 0xaa still executed, since the tx is still ongoing, but doesn't redo the selfdestruct, it takes a different path if callvalue is non-zero)

  • Tx 2:

    • sender does a 5-wei call to 0xaa. No exec (since no code).

In geth, the result would be that 0xaa had 6 wei, whereas OE reported (correctly) 5 wei. Furthermore, in geth, if the second tx was not executed, the 0xaa would be destructed, resulting in 0 wei. Thus obviously wrong.

It was determined that the root cause was this commit from this PR. The semantics of createObject was subtly changd, into returning a non-nil object (with deleted=true) where it previously did not if the account had been destructed. This return value caused the new object to inherit the old balance:

func (s *StateDB) CreateAccount(addr common.Address) {
	newObj, prev := s.createObject(addr)
	if prev != nil {
		newObj.setBalance(prev.data.Balance)
	}
}

It was determined that the minimal possible correct fix was

+++ b/core/state/statedb.go
@@ -589,7 +589,10 @@ func (s *StateDB) createObject(addr common.Address) (newobj, prev *stateObject)
                s.journal.append(resetObjectChange{prev: prev, prevdestruct: prevdestruct})
        }
        s.setStateObject(newobj)
-       return newobj, prev
+       if prev != nil && !prev.deleted {
+               return newobj, prev
+       }
+       return newobj, nil

Patches

See above. The fix was included in Geth v1.9.20 "Paragade".

Credits

The bug was found by @johnyangk and reported via bounty@ethereum.org.

For more information

If you have any questions or comments about this advisory:

Risk Scores
Base Score
5.3

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the integrity of the data.

Threat Intelligence
4.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.91%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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