Medium severity · published Oct 21, 2026
CVE-2021-48019
Vyper before 0.2.9 Incorrect RETURNDATASIZE in create_forwarder_to Proxies
4.8
CVSS
0.2%
EPSS
No
On KEV
Description
Vyper before 0.2.9 deploys forwarder proxies through the built-in create_forwarder_to function that report a fixed 4096-byte RETURNDATASIZE rather than the actual return data size. Calls through these proxies can yield corrupted data when a function returns more than 4096 bytes without return data sanitation, and fail strict return-size checks such as SafeERC20.safeTransfer.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
VY
vyper · vyperlang
before 0.2.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-48019
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-48019
github.com
https://github.com/vyperlang/vyper/security/advisories/GHSA-375m-5fvv-xq23
www.vulncheck.com
https://www.vulncheck.com/advisories/vyper-before-0.2.9-incorrect-returndatasize-in-create-forwarder-to-proxies
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