Bug 2561987 (CVE-2026-117601)

Summary: CVE-2026-117601 electrum: Electrum before 4.8.3 Missing Signature Verification of Mempool Transactions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in electrum. A connected malicious server can exploit this vulnerability to cause theft of funds by replacing a legitimate transaction with a fraudulent transfer. Because the application fails to verify cryptographic signatures on unconfirmed transactions, the attacker can display a spoofed transaction paying an attacker-controlled address. This issue allows the server to deceive the user into signing a fee adjustment, resulting in the unauthorized transfer of funds.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2562802, 2562804, 2562805, 2562806    
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Description OSIDB Bzimport 2026-10-27 14:00:33 UTC
Electrum before 4.8.3 fails to verify signatures of wallet-owned inputs in unconfirmed mempool transactions, allowing malicious servers to replace a just-broadcast transaction with a conflicting one. Attackers can swallow the user's transaction and display an invalid zero-fee copy paying an attacker address, tricking users into RBF fee-bumping and signing it.