CVE-2026-90771 PUBLISHED

joi before 17.13.8 and 18.2.9 Prototype Pollution via messages

Assigner: VulnCheck
Reserved: 13.09.2026 Published: 13.09.2026 Updated: 13.09.2026

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts proto as an error code. Attackers can supply proto keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

CVSS Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	Low	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS Score: 3.7

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	Low
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	hapijs
Product	joi
Versions	Default: unaffected affected from 16.0.0 to 17.13.8 (excl.) affected from 18.0.0 to 18.2.9 (excl.)

Credits

George Chen reporter

References

Problem Types

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') CWE