Vulnerability in io.netty:netty-handler-ssl-ocsp (CVE-2026-56822)
Summary
Vulnerability in io.netty:netty-handler-ssl-ocsp (CVE-2026-56822). Confidential information can be exposed externally. Exploitable via SslHandshakeCompletionEvent. Mitigation: upgrade to 4.1.136.Final or later.
Original description
The description as published by the source.
Summary
Netty's OcspServerCertificateValidator forwards the SslHandshakeCompletionEvent before the asynchronous OCSP validation completes. This allows the client's downstream handlers to send sensitive application data (e.g., HTTP requests) to a revoked server before the channel is closed by the OCSP check.
Details
In io.netty.handler.ssl.ocsp.OcspServerCertificateValidator#userEventTriggered, when an SslHandshakeCompletionEvent is received, the validator immediately calls ctx.fireUserEventTriggered(evt). It then initiates an asynchronous OCSP query using OcspClient.query.
Because the handshake completion event is forwarded immediately, downstream handlers in the client's pipeline are notified that the TLS handshake is successful. They may then begin reading and processing incoming application data or sending outgoing data. If the OCSP response later indicates the server's certificate is REVOKED, the validator closes the channel, but by this time, the client may have already leaked sensitive data to a revoked server or processed malicious responses from it.
PoC
@Test
public void test() throws Exception {
EventLoopGroup group = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
try {
OCSPRespBuilder respBuilder = new OCSPRespBuilder();
OCSPResp response = respBuilder.build(OCSPRespBuilder.INTERNAL_ERROR, null);
byte[] responseEncoded = response.getEncoded();
IoTran…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-56822 has been found in io.netty:netty-handler-ssl-ocsp.
Attackers can target a specific entry point like SslHandshakeCompletionEvent over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.4/10.
What to do: upgrade io.netty:netty-handler-ssl-ocsp to 4.1.136.Final or later.
If unsure, ask your IT team or search "io.netty:netty-handler-ssl-ocsp CVE-2026-56822" on the vendor's site.
CVE-2026-56822 (io.netty:netty-handler-ssl-ocsp) — CWE-367 / CVSS v3 7.4
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: SslHandshakeCompletionEvent / OcspClient.query
Patched: 4.1.136.Final — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-367) exists in io.netty:netty-handler-ssl-ocsp. Attackers reach the vulnerable code path via SslHandshakeCompletionEvent without authentication.
Check the vendor advisory for the affected versions of io.netty:netty-handler-ssl-ocsp. Attack surface: SslHandshakeCompletionEvent / OcspClient.query.
Severity: High (CVSS 7.4/10). Confidential information can be exposed externally.
Update to 4.1.136.Final.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで io.netty:netty-handler-ssl-ocsp を使っているサービスとバージョンを洗い出す。
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2Apply patch patch
Upgrade io.netty:netty-handler-ssl-ocsp to 4.1.136.Finalステージング環境で 4.1.136.Final に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-56822 netty
- Ubuntu UBUNTU-CVE-2026-56822 netty
References
- patch github.com
- web github.com
- web github.com
- web github.com