How severe is CVE-2026-54251?

No CVSS score has been assigned to CVE-2026-54251 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-54251?

CVE-2026-54251 affects the following packages: io.netty.incubator:netty-incubator-codec-ohttp (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-54251?

Update io.netty.incubator:netty-incubator-codec-ohttp to 0.0.23.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54251 is resolved across your whole dependency graph.

How do I detect CVE-2026-54251 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty.incubator:netty-incubator-codec-ohttp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-54251 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-54251 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-54251 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-54251?

CVE-2026-54251 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 41th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-54251?

CVE-2026-54251 is classified as CWE-664 (CWE-664). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-54251 published, and has it been updated?

CVE-2026-54251 was published on September 15, 2026 and was last updated on October 2, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-54251: Info Disclosure — Fixed in 0.0.23.Final

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54251.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs41th percentile — riskier than 41% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

☕io.netty.incubator:netty-incubator-codec-ohttp

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

netty-incubator-codec-ohttp implements Oblivious HTTP (OHTTP) gateway and client functionality using Netty. Prior to 0.0.23.Final, the OHTTP gateway decryption path in codec-ohttp/src/main/java/io/netty/incubator/codec/ohttp/OHttpRequestResponseContext.java allocates a pooled direct ByteBuf for decrypted plaintext before the AEAD tag is verified. When an invalid tag causes decryptChunk() to throw CryptoException, OHttpRequestResponseContext.decodeChunk() does not release the ByteBuf because the allocation is not guarded by try/finally. Repeated invalid encrypted requests can therefore leak native off-heap memory until the gateway is unable to continue serving requests. This issue is fixed in version 0.0.23.Final.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.netty.incubator:netty-incubator-codec-ohttp`	all versions	0.0.23.Final`io.netty.incubator:netty-incubator-codec-ohttp:0.0.23.Final`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty.incubator:netty-incubator-codec-ohttp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty.incubator:netty-incubator-codec-ohttp to 0.0.23.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54251 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

netty-incubator-codec-ohttp implements Oblivious HTTP (OHTTP) gateway and client functionality using Netty. Prior to 0.0.23.Final, the OHTTP gateway decryption path in codec-ohttp/src/main/java/io/netty/incubator/codec/ohttp/OHttpRequestResponseContext.java allocates a pooled direct ByteBuf for decrypted plaintext before the AEAD tag is verified. When an invalid tag causes decryptChunk() to throw CryptoException, OHttpRequestResponseContext.decodeChunk() does not release the ByteBuf because the allocation is not guarded by try/finally. Repeated invalid encrypted requests can therefore leak nat

O3 Security · Impact-Aware SCA

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CVE-2026-54251 — netty-incubator-codec-oht…