CVE-2026-117601
HIGH
NVD
CVSS Score
7.5
Severity
HIGH
Published
Oct 27, 2026
Vendor
unknown
Description
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.