Unrated

Unauthenticated CPU-exhaustion DoS in Netty BinaryHttpParser

IdentifiersCVE-2026-63202CWE-835

CVE-2026-63202 is an unauthenticated denial-of-service vulnerability in netty-incubator-codec-bhttp and netty-incubator-codec-ohttp affecting BinaryHttpParser during Binary HTTP field-section decoding. The flaw is caused by an infinite loop condition in parser logic that continues processing while the remaining field-section length is not equal to zero, rather than only while it is greater than zero. When a crafted Binary HTTP message causes field-line parsing to make no forward progress, the parser can loop indefinitely instead of terminating with a framing error. Additional unsafe handling includes failure to treat null or zero-progress returns from field-line parsing as fatal errors, insufficient rejection of field lines that consume more than the declared field-section length, and reliance on assert-based invariant checks rather than explicit exception handling. Successful exploitation allows a remote attacker to trigger an infinite loop before business-logic processing occurs.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

A remote unauthenticated attacker can force a vulnerable parser instance into an infinite loop that permanently consumes a Netty event-loop thread at full CPU utilization. Because Netty commonly multiplexes many connections and requests across a limited number of event-loop threads, a small number of malicious requests can exhaust available event-loop capacity and render an affected OHTTP gateway or client unavailable. The impact is high on availability, with no indicated direct effect on confidentiality or integrity.

Mitigation

If you can’t patch tonight, do this now.

No complete workaround short of applying the code fix is available. As interim risk reduction, minimize public exposure of reachable OHTTP gateways and clients where operationally feasible, and monitor for sustained CPU saturation or hung Netty event-loop threads indicative of exploitation. Input-size controls such as maximum field-section size do not prevent exploitation because the flaw is triggered in parser control flow before normal business-logic safeguards can mitigate it.

Remediation

Patch, then assume compromise.

Upgrade netty-incubator-codec-bhttp and netty-incubator-codec-ohttp to version 0.0.23.Final or later. The corrective changes should ensure the field-section decoding loop only continues while the remaining length is greater than zero, treat null or zero-progress results from field-line parsing as hard framing errors, reject field lines that exceed the declared field-section length, and replace assert-based invariant enforcement with explicit exception handling so malformed input cannot trap the parser in a non-terminating state.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

NettyNetty-Incubator-Codec-Bhttpapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

No public activity tracked yet. Mallory keeps watching.

0 SOURCESView more in app

No public activity observed for this vulnerability.

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity