CVE-2026-48040
CRITICALThe netty incubator codec.bhttp is a java language binary http parser. The library implements Oblivious HTTP (RFC 9458) using BoringSSL's HPKE C library via JNI. When deriving native…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
The netty incubator codec.bhttp is a java language binary http parser. The library implements Oblivious HTTP (RFC 9458) using BoringSSL's HPKE C library via JNI. When deriving native memory addresses for cryptographic operations versions prior to 0.0.22.Final provide a fallback path for direct ByteBufs that do not expose their memory address through hasMemoryAddress(). This fallback occurs when sun.misc.Unsafe is unavailable to Netty — for example, when the JVM is started with -Dio.netty.noUnsafe=true, when a SecurityManager restricts Unsafe access, or when running on non-HotSpot JVMs. In these configurations, Netty's default PooledByteBufAllocator returns PooledDirectByteBuf instances for which hasMemoryAddress() returns false. Under the enabling JVM configuration, an unauthenticated network attacker can cause the OHTTP gateway to corrupt memory belonging to other concurrent connections and disclose the contents of adjacent pooled direct buffers by triggering cryptographic operations with crafted OHTTP requests. The corruption occurs regardless of whether the AEAD tag verification succeeds, as BoringSSL zeroizes the output buffer on failure. The information disclosure path provides the attacker with the encryption key needed to extract the leaked data. This violates the confidentiality and integrity of all connections sharing the same Netty buffer arena. Version 0.0.22.Final fixes the issue.
Affected Products
netty-incubator-codec-ohttpnettyDetection & mitigation playbook
Vendor / applianceDetect
Inventory every netty netty-incubator-codec-ohttp deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the netty netty-incubator-codec-ohttp security patch or hotfix for CVE-2026-48040 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-48040 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-48040. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-48040 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-48040 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.