by Kastro
Paper/Archive/CVE-2025-27105

CVE-2025-27105

vyperlang vyper — AugAssign evaluation order causing OOB write within the object in Vyper

EPSS 0.6%CVSS 9.1
critical.is priorityof 100
37
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 47.2.472 × 209.4No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
vyper< 0.4.1–CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
GitHub_M (CNA)2.3CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgithub.com/vyperlang/vyper/security/advisories/GHSA-4w26-8p97-f4jp