CVE-2026-117601: Electrum before 4.8.3 Missing Signature Verification of Mempool Transactions

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 27 Oct 2026. It cites 1 public report, the first from 27 Oct 2026.

• github.com

How likely is exploitation in the next 30 days?

0.2%

EPSS score, percentile 7.1 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

9.3 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (2)

Which versions are affected?

Affected

• before 4.8.3

Unaffected 4.8.3

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

Electrum before 4.8.3 Missing Signature Verification of Mempool Transactions

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.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

• Patch Commit (Patch)
• GitHub Security Advisory (GHSA-6jp4-8v48-cc5v) (Vendor advisory)

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline