Electrum 4.8.3 Patch Addresses High-Severity Bitcoin Wallet Vulnerability

Cryptoticker

Electrum 4.8.3 Patch Addresses High-Severity Bitcoin Wallet Vulnerability

First seen 25 Oct 2026, 16:13 UTC • •66.0

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ThreatCluster •October 25, 2026 at 18:13 UTC

•Electrum 4.8.3 fixes a high-severity vulnerability affecting all prior versions.
•At least two users reported Bitcoin theft due to the flaw's exploitation.
•The vulnerability allowed attackers to replace legitimate transactions with fraudulent ones.

Electrum has released version 4.8.3 to address a high-severity vulnerability that allowed malicious servers to redirect user payments. The flaw affected all versions prior to 4.8.3, with at least two confirmed incidents of stolen Bitcoin. Attackers exploited the wallet's handling of unconfirmed transactions, allowing them to replace legitimate payments with fraudulent ones. Users could inadvertently authorize these fraudulent transactions while attempting to increase transaction fees. The vulnerability was disclosed on October 24, 2026, after developers confirmed its exploitation in the wild. The patch verifies signatures on unconfirmed transactions to prevent such attacks. Electrum is a lightweight wallet that relies on external servers for transaction histories, making it susceptible to this type of attack. Developers have not disclosed the total losses incurred from the exploit.

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Timeline

2026-10-11

User reports suspicious transaction

A user reported that a transaction displayed in Electrum's history did not match the payment originally submitted.

2026-10-18

Second user reports loss

Another user contacted developers after losing funds while attempting to increase a transaction fee, revealing the exploit's impact.

2026-10-23

Electrum 4.8.3 released

Electrum developers released version 4.8.3 to patch the high-severity vulnerability.

2026-10-24

Security advisory published

Developers disclosed the vulnerability and its exploitation in a security advisory following the patch release.

More articles in this cluster (4)

Threat Graph

3 entities, 2 inferred relationships (STIX 2.1).

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Threat Actor (1)

Electrum

Technique (1)

Data Breach

Weakness (1)

CWE-287 - Improper Authentication

Relationships

Electrum uses Data Breach
Electrum related to CWE-287 - Improper Authentication

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Common questions

Which versions of Electrum are affected?

All versions prior to 4.8.3 are affected by the vulnerability.

What should users do now?

Users should immediately update to Electrum version 4.8.3 to mitigate the vulnerability.

How many incidents have been confirmed?

At least two incidents of Bitcoin theft have been confirmed due to the vulnerability.

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