CVE-2026-69205 Http4s - Server Side Request Forgery

Http4s prior to 0.23.35 and 1.0.0-M47 contains a server-side request forgery caused by case-sensitive substring test and improper charset decoding in Ember's HeaderP.parse, letting attackers perform request smuggling and cache poisoning, exploit requires crafted HTTP requests.

CVSS base score 8.7 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.48% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Server Side Request Forgery
Impact
Server Side Request Forgery
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Published
15 September 2026
Updated
15 October 2026
Weakness
CWE-444

Vendor fix

Upgrade to versions 0.23.35 or 1.0.0-M47 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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