CVE-2026-117601

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductElectrum

PublishedOct 27, 2026

First seenOct 27, 2026

Weakness typeCWE-347CWE-347

How to fix

Update

electrum4.8.3 or later

Patches

github.com/spesmilo/electrum/commit/90fe30822561e515a9d2d6e5a352cc07780999eb

Vendor advisories

github.com/spesmilo/electrum/security/advisories/GHSA-6jp4-8v48-cc5v

Affected products

Product	Affected versions	Fixed in
electrumPyPI	v < 4.8.3	4.8.3

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.