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.
Published: 2026-10-27
Score: 9.3 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-6jp4-8v48-cc5v Electrum: Malicious server can replace a just-broadcast tx and try to trick user into RBF-ing it
History

Wed, 28 Oct 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 27 Oct 2026 13:45:00 +0000

Type Values Removed Values Added
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.
Title Electrum before 4.8.3 Missing Signature Verification of Mempool Transactions
First Time appeared Electrum
Electrum electrum
Weaknesses CWE-347
CPEs cpe:2.3:a:electrum:electrum:*:*:*:*:*:*:*:*
Vendors & Products Electrum
Electrum electrum
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

Electrum Electrum
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-28T16:16:43.752Z

Reserved: 2026-10-27T13:04:09.905Z

Link: CVE-2026-117601

cve-icon Vulnrichment

Updated: 2026-10-28T15:56:47.895Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-27T14:16:39.947

Modified: 2026-10-28T17:18:17.600

Link: CVE-2026-117601

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-27T16:15:04Z

Weaknesses