CVE-2025-26622Public exploitNetwork attack vector

Incorrect contract decisions via rounded-up square roots

Published Feb 21, 2025 · Updated Feb 22, 2025

Incorrect calculation in Vyper before 0.4.1 allows attackers to obtain rounded-up decimal square-root results via crafted inputs. The sqrt() built-in's Babylonian loop can finish while its approximation oscillates between adjacent fixed-point values, returning the higher value instead of consistently rounding down. Reachability requires a contract compiled with an affected release to use sqrt() on attacker-controlled decimals in boundary logic, where the erroneous result can select the wrong contract branch.

CVSS severity2.3
Low
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect calculation in Vyper before 0.4.1 allows attackers to obtain rounded-up decimal square-root results via crafted inputs. The sqrt() built-in's Babylonian loop can finish while its approximation oscillates between adjacent fixed-point values, returning the higher value instead of consistently rounding down. Reachability requires a contract compiled with an affected release to use sqrt() on attacker-controlled decimals in boundary logic, where the erroneous result can select the wrong contract branch.

The record

CVE
CVE-2025-26622
Published
Feb 21, 2025
Updated
Feb 22, 2025
Vendor
Vyper
Product
Vyper
Classifications
CWE-682
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Vyper · Vyperversion=< 0.4.1

Published CVSS scores

2.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-682Incorrect Calculation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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