CVE-2026-59900 - Vulnerability Details - OpenCVE

A flaw was found in Netty's netty-codec-http2 component. The HTTP/2 encoder does not properly handle special characters in HTTP headers. This vulnerability allows a remote attacker to craft specific HTTP/2 requests, leading to HTTP response splitting and header injection attacks. Such attacks can enable an attacker to manipulate web content or inject malicious headers.

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

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Project Subscriptions

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Advisories

Source	ID	Title
Github GHSA	GHSA-c69g-56f8-xwqj	Netty: [codec-http2] Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References

Link	Providers
https://nvd.nist.gov/vuln/detail/CVE-2026-59900
https://www.cve.org/CVERecord?id=CVE-2026-59900

History

Tue, 28 Jul 2026 00:15:00 +0000

Type	Values Removed	Values Added
Description		A flaw was found in Netty's netty-codec-http2 component. The HTTP/2 encoder does not properly handle special characters in HTTP headers. This vulnerability allows a remote attacker to craft specific HTTP/2 requests, leading to HTTP response splitting and header injection attacks. Such attacks can enable an attacker to manipulate web content or inject malicious headers.
Title		io.netty/netty-codec-http2: Netty: Improper header neutralization in netty-codec-http2
References		https://nvd.nist.gov/vuln/detail/CVE-2026-59900 https://www.cve.org/CVERecord?id=CVE-2026-59900
Metrics	threat_severity `None`	cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'}` threat_severity `Moderate`

Projects

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MITRE

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Vulnrichment

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NVD

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Redhat

Severity : Moderate

Publid Date: 2026-07-09T00:00:00Z

Links: CVE-2026-59900 - Bugzilla

OpenCVE Enrichment

No data.

Weaknesses

No weakness.

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["https://www.cve.org/CVERecord?id=CVE-2026-59900\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-59900"], "statement": "This Moderate impact flaw in Netty's HTTP/2 encoder allows attackers to inject arbitrary header content via specially crafted HTTP/2 requests. 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