CVE-2026-27959

high Red Hat
CVSS v3 Base Score
8.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
EPSS Score
0.1%
Exploitation probability in 30 days
Top 70% most likely to be exploited
Attack Characteristics
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
High
Availability
None
Published: February 26, 2026 (77 days ago)
Last Modified: February 26, 2026
Vendor: Red Hat

Description

Koa is middleware for Node.js using ES2017 async functions. Prior to versions 3.1.2 and 2.16.4, Koa's `ctx.hostname` API performs naive parsing of the HTTP Host header, extracting everything before the first colon without validating the input conforms to RFC 3986 hostname syntax. When a malformed Host header containing a `@` symbol is received, `ctx.hostname` returns `evil[.]com` - an attacker-controlled value. Applications using `ctx.hostname` for URL generation, password reset links, email verification URLs, or routing decisions are vulnerable to Host header injection attacks. Versions 3.1.2 and 2.16.4 fix the issue.

CWE

CWE-20

Affected Products

Red Hat Developer HubRed Hat OpenShift AI (RHOAI)Red Hat OpenShift Container Platform 4Red Hat OpenShift Dev SpacesSelf-service automation portal 2

References

🔗 bugzilla.redhat.com 🔗 www.cve.org 🔗 nvd.nist.gov 🔗 github.com 🔗 github.com