CVE-2025-27105

Description

vyper is a Pythonic Smart Contract Language for the EVM. Vyper handles AugAssign statements by first caching the target location to avoid double evaluation. However, in the case when target is an access to a DynArray and the rhs modifies the array, the cached target will evaluate first, and the bounds check will not be re-evaluated during the write portion of the statement. This issue has been addressed in version 0.4.1 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Weakness Type (CWE)

CWE-787 Out-of-bounds Write

Affected Products

Vendor	Product	Versions
vyperlang	vyper	< 0.4.1

References

Advisories & Patches

https://github.com/vyperlang/vyper/security/advisories/GHSA-4w26-8p97-f4jp

Exploits

https://github.com/vyperlang/vyper/security/advisories/GHSA-4w26-8p97-f4jp

Frequently Asked Questions

What is CVE-2025-27105? +

vyper is a Pythonic Smart Contract Language for the EVM. Vyper handles AugAssign statements by first caching the target location to avoid double evaluation. However, in the case when target is an access to a DynArray and the rhs modifies the array, the cached target will evaluate first, and the bounds check will not be re-evaluated during the write portion of the statement. This issue has been addressed in version 0.4.1 and all users are advised to upgrade. There are no known workarounds for this vulnerability. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2025-27105? +

CVE-2025-27105 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2025-27105? +

CVE-2025-27105 affects products from vyperlang, specifically: vyper. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-27105? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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