Paper/Archive/CVE-2026-117601

CVE-2026-117601

spesmilo electrum — Electrum before 4.8.3 Missing Signature Verification of Mempool Transactions

CVSS 9.3 (CNA)9.3 / 10 × 3027.9 Not in CISA KEV+300.0 EPSS percentile 7.1.071 × 201.4 No public exploit+100.0 SSVC exploitation: none+100.0

Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource

electrum< 4.8.34.8.3CNA

Scores by source

VulnCheck (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

VulnCheck (CNA)7.5CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

advisorygithub.com/spesmilo/electrum/security/advisories/GHSA-6jp4-8v48-cc5v patchgithub.com/spesmilo/electrum/commit/90fe30822561e515a9d2d6e5a352cc07780999eb writeupvulncheck.com/advisories/electrum-before-4.8.3-missing-signature-verification-of-mempool-transactions