CVE-2026-425787.5HighCWE-113

CVE-2026-42578: Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

netty

Vendor fix available · Affected: netty · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

1.1%probability of exploitation in the next 30 days

65th percentile

050100

Higher than 65% of scored CVEs

7.5HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's HttpProxyHandler constructs HTTP CONNECT requests with header validation explicitly disabled. The newInitialMessage() method creates headers using DefaultHttpHeadersFactory.headersFactory().withValidation(false), then adds user-provided outboundHeaders without any CRLF validation. This allows an attacker who can influence the outbound headers to inject arbitrary HTTP headers into the CONNECT request sent to the proxy server. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

netty · netty>= 4.2.0.Alpha1, < 4.2.13.Final; < 4.1.133.Final

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Neutralization of CRLF Sequences in HTTP Headers · Injection and Smuggling
Vendor: netty
Published: May 2026
Band: Possible (1 to 10%), May 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-42578 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

8 more references are in the CVE record.