Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:3482-1 advisory.

    Upgrade netty to upstream version 4.1.136 and netty-tcnative to version 2.0.80 Final.

    Security issues fixed

    - CVE-2026-44891: memory exhaustion in `io.netty:netty-codec-stomp` (bsc#1271435).
    - CVE-2026-55831: resource exhaustion/DoS in `io.netty:netty-codec-http` (bsc#1271960).
    - CVE-2026-55833: zip bomb in `io.netty:netty-codec-http` (bsc#1271961).
    - CVE-2026-55851: memory exhaustion in `io.netty:netty-codec-haproxy` (bsc#1272253).
    - CVE-2026-56745: memory exhaustion in `io.netty:netty-codec-http` (bsc#1272254).
    - CVE-2026-56746: improper access control in `io.netty:netty-codec-http` (CORS) (bsc#1272255).
    - CVE-2026-56817: insecure defaults in XML parsing in `io.netty:netty-codec-xml` (bsc#1272257).
    - CVE-2026-56818: memory leak in `io.netty:netty-codec-redis` (bsc#1272603).
    - CVE-2026-56819: memory leak in `io.netty:netty-codec-http2` (bsc#1272258).
    - CVE-2026-56820: improper certificate validation in `io.netty:netty-handler-ssl-ocsp` (bsc#1272259).
    - CVE-2026-56821: improper certificate revocation check in `io.netty:netty-handler-ssl-ocsp`     (bsc#1272299).
    - CVE-2026-56822: time-of-check/time-of-use in `io.netty:netty-handler-ssl-ocsp` (bsc#1272300).
    - CVE-2026-59898: protocol version confusion in `io.netty:netty-codec-http` (websocket) (bsc#1272302).
    - CVE-2026-59899: memory exhaustion in `io.netty:netty-codec-http` (bsc#1272301).
    - CVE-2026-59900: improper header neutralization in `io.netty:netty-codec-http2` (bsc#1272303).
    - CVE-2026-59901: infinite loop in `io.netty:netty-codec-compression` (bzip2) (bsc#1272304).
    - CVE-2026-59919: improper CR/LF neutralization in `io.netty:netty-codec-haproxy` (bsc#1272305).
    - CVE-2026-59920: improper CR/LF neutrolization in `io.netty:netty-codec-stomp` (bsc#1272306).
    - CVE-2026-59921: improper CR/LF neutralization in `io.netty:netty-codec-http` (multipart) (bsc#1272307).
    - Memory leak in `io.netty:netty-codec-dns`  (bsc#1272519).
    - Uncontrolled resource consumption in `io.netty:netty-codec-xml` (bsc#1272518).

    Other updates and bugfixes:

    - Upgrade to upstream version 4.1.136:
      - SingleThreadEventExecutor: document Throwable safety contract         on run()
      - Make HTTP/2 frame hashCode consistent with equals
      - Add BlockHound exception for DnsQueryIdSpace (#16896)
      - FlowControlHandler: Fix autoRead behavior
      - Fix incorrect bounds in error message of         HpackDecoder.setMaxHeaderListSize
      - MQTT: Fix MQTT decoder size check after variable header replay
      - MQTT: Make the decodeProperties early-REPLAY check actually         fire
      - Reject control characters at the boundary of HTTP method names         (#16723)
      - Update to latest tcnative release
      - Fix HTTP 2 PUSH_PROMISE stream association validation
      - Fix GZIP FEXTRA extra-field handling in JdkZlibDecoder
      - Add opt-in validation of mandatory pseudo-header fields for         HTTP/2
      - Strictly validate MQTT UTF-8 Encoded String (#16939)
      - Stop DateFormatter trailing token from running past the parse         end
      - IpFilter: Deprecate constructor which use accept by default
      - Add RFC 10008 QUERY Method support (#16966)
      - Correctly release and fail queued traffic-shaping writes on         close (#16959)
      - FlowControlHandler: respect auto-read when toggled while         dequeueing
      - IdleStateHandler: reset firstWriter/ReaderIdleEvent in         resetWriteTimeout/resetReadTimeout (#16982)
      - Fix typo in AbstractSniHandler Javadoc
      - Reconcile AbstractCoalescingBufferQueue readableBytes when it         drains, and fail stuck HTTP/2 streams instead of spinning         empty DATA frames
      - Reject control characters at the boundary of the HTTP version         token (#16971)
      - Reset UTF-8 decode state on CR in StompSubframeDecoder
      - HTTP2: Pass the correct number of arguments when logging         goaway       + FastLz: Guard decompression against truncated input (#17000)       + Fix propagation of startTls for client SslContext handler       + Reject non-token characters in HTTP/2 header names       + Update lz4-java to 1.11.1       + Pin github actions to reduce risk (#17043)       + Merge branches from forks (#17063)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and     4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop     processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay     a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to     certificate revocation bypass via replay of an expired OCSP response. Any application using     OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been     fixed in versions 4.1.136.Final and 4.2.16.Final. (CVE-2026-56821)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and
    4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop
    processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay
    a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to
    certificate revocation bypass via replay of an expired OCSP response. Any application using
    OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been
    fixed in versions 4.1.136.Final and 4.2.16.Final. (CVE-2026-56821)

ID	Name	Product	Family	Type	Severity
332130	SUSE SLED15 / SLES15 Security Update : netty, netty-tcnative (SUSE-SU-2026:3482-1)	Nessus	SuSE Local Security Checks	Local	high
330647	Linux Distros Unpatched Vulnerability : CVE-2026-56821	Nessus	Misc.	Local	high
445178	SCA: security update for io.netty:netty-handler-ssl-ocsp (GHSA-g7hg-vrcf-mvmr)	Tenable Cloud Security	SCA Checks	Local	high
445178	SCA: security update for io.netty:netty-handler-ssl-ocsp (GHSA-g7hg-vrcf-mvmr)	Tenable Self-Hosted Container Security	SCA Checks	Local	high

Detections

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CVE-2026-56821

high

Tenable Plugins

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high

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