CVE-2026-117601

CVSS 9.3 (critical) · published 2026-10-27

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.

Weakness: CWE-347

Source: NVD CVE-2026-117601

References

• https://github.com/spesmilo/electrum/commit/90fe30822561e515a9d2d6e5a352cc07780999eb
• https://github.com/spesmilo/electrum/security/advisories/GHSA-6jp4-8v48-cc5v
• https://www.vulncheck.com/advisories/electrum-before-4.8.3-missing-signature-verification-of-mempool-transactions

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