Low severity · published Sep 13, 2026
CVE-2026-90771
joi before 17.13.8 and 18.2.9 Prototype Pollution via messages
3.7
CVSS
0.4%
EPSS
No
On KEV
Description
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:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 33% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JO
joi · hapijs
16.0.0 before 17.13.8; 18.0.0 before 18.2.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-90771
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-90771
github.com
https://github.com/hapijs/joi
github.com
https://github.com/hapijs/joi/blob/v18.2.8/lib/messages.js
github.com
https://github.com/hapijs/joi/commit/5b8333c9177e08b4ef4ed02903c2d657084e7afb
github.com
https://github.com/hapijs/joi/issues/3150
www.vulncheck.com
https://www.vulncheck.com/advisories/joi-before-17.13.8-and-18.2.9-prototype-pollution-via-messages
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