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TI-2026-81176 Aliases CVE-2026-117601GHSA-6jp4-8v48-cc5v

Missing signature verification of mempool transactions in Electrum

Priority MEDIUM 47CWE-347Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-347.

Summary

Electrum before 4.8.3 does not verify signatures of wallet-owned inputs in unconfirmed mempool transactions, which is classified as CWE-347. A malicious server can replace a broadcast transaction with a conflicting one and show a zero-fee copy that pays an attacker address. An unauthenticated remote attacker can use this to trick users into fee-bumping and signing the replacement.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00176 7th percentileScored 2026-11-07
Fix Fixed electrum (spesmilo): 4.8.3electrum (PyPI): 4.8.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
spesmiloelectrumbefore 4.8.34.8.3Patch availableCNA
—electrum (PyPI)before 4.8.34.8.3Patch availableGHSA-6jp4-8v48-cc5v
  • electrum Vendorspesmilo Affected before 4.8.3 Fixed in 4.8.3 Patch available CNA
  • electrum (PyPI) Vendor— Affected before 4.8.3 Fixed in 4.8.3 Patch available GHSA-6jp4-8v48-cc5v

Remediation

Update Electrum to 4.8.3, the fixed version for both the spesmilo electrum and PyPI electrum packages.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA electrum (spesmilo) Fixed in 4.8.3
  • Fix · GHSA-6jp4-8v48-cc5v electrum (PyPI) Fixed in 4.8.3 Advisory →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-27 Threatist record created from CVE-2026-117601
  2. 2026-10-28 CISA SSVC decision points changed
  3. 2026-10-28 Alias added: GHSA-6jp4-8v48-cc5v
  4. 2026-10-28 Fix available: PyPI/[email protected] · GHSA-6jp4-8v48-cc5v
  5. 2026-10-28 CVSS score added · GHSA-6jp4-8v48-cc5v
  6. 2026-10-28 Weakness changed · GHSA-6jp4-8v48-cc5v
  7. 2026-10-28 5 new references · GHSA-6jp4-8v48-cc5v
  8. 2026-10-29 Affected versions changed · Red Hat
  9. 2026-10-29 CVSS score added · Red Hat

References

Patch 1

Advisory 2

Other 2

  • TI-2026-81178 Spending limit bypass in Electrum Nostr Wallet Connect plugin CVSS 4.0CRITICAL 9.3
  • TI-2026-81177 Electrum external plugin authorization bypass enables local code execution CVSS 4.0HIGH 8.6

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences