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VulnerabilityPublished

CVE-2026-117601: spesmilo electrum · Improper Verification of Cryptographic Signature

Affects spesmilo electrumSource CVE Database V5

0

Not known to be exploited · CVSS 9.3 Critical : upgrade to 4.8.3 as a priority.

Data as of 27 Oct 2026, 13:57 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 4.8.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade electrum and spesmilo/electrum to 4.8.3.

Affected software

ProductAffectedFixed in
spesmiloelectrumAffected
  • <4.8.3
Fixed in
  • 4.8.3
GitHubspesmilo/electrumpkg:github/spesmilo/electrumOther threatsAffected
  • <4.8.3
Fixed in
  • 4.8.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Electrum to version 4.8.3 or later, where the signature verification issue is fixed. No other mitigations are indicated by the vendor advisory.

Description

Electrum versions before 4.8.3 have a vulnerability where the software fails to verify signatures of wallet-owned inputs in unconfirmed mempool transactions. This flaw allows malicious servers to replace a user's just-broadcast transaction with a conflicting transaction that appears to have zero fees and pays an attacker address. Users can be tricked into performing Replace-By-Fee (RBF) fee-bumping on this invalid transaction, effectively losing funds to the attacker. The issue is fixed in Electrum version 4.8.3.

References

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