CVE-2026-93567: Input Validation Flaw (CVSS 7.5)

Description

A flaw was found in Netty's HTTP/2 codec. When converting HTTP/1 CONNECT requests to HTTP/2, the component incorrectly uses the Host header instead of the CONNECT authority-form request-target for the tunnel authority. A remote attacker can exploit this by supplying a different Host header, leading to a malformed HTTP/2 CONNECT request. This can bypass security controls such as tunnel allow-lists or egress policies, resulting in integrity loss.

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CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0152

Probability of exploitation

0.74%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

References

Other References

https://access.redhat.com/errata/RHSA-2026:69440 https://access.redhat.com/errata/RHSA-2026:69470 https://access.redhat.com/errata/RHSA-2026:70257 https://access.redhat.com/security/cve/CVE-2026-93567 https://bugzilla.redhat.com/show_bug.cgi?id=2536955

Frequently Asked Questions

What is CVE-2026-93567? +

A flaw was found in Netty's HTTP/2 codec. When converting HTTP/1 CONNECT requests to HTTP/2, the component incorrectly uses the Host header instead of the CONNECT authority-form request-target for the tunnel authority. A remote attacker can exploit this by supplying a different Host header, leading to a malformed HTTP/2 CONNECT request. This can bypass security controls such as tunnel allow-lists or egress policies, resulting in integrity loss. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-93567? +

CVE-2026-93567 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0152, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-93567? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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