{"answers":{"affected":"4 open source packages ship an affected version, including io.netty:netty-handler-ssl-ocsp. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56821 exists.","fix":"Upgrade io.netty:netty-handler-ssl-ocsp to a fixed version for your release line: 4.1.136.Final or 4.2.16.Final.","what":"CVE-2026-56821 is a high-severity vulnerability in Netty Netty, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-56821 and fix it if it is affected.\n\nWhat it is: CVE-2026-56821 is a high-severity vulnerability in Netty Netty, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56821 exists.\n\nAffected packages and fixed versions:\n- io.netty:netty-handler-ssl-ocsp (Maven): affected all versions; fixed in 4.1.136.Final\n- io.netty:netty-handler-ssl-ocsp (Maven): affected all versions; fixed in 4.1.136.Final\n- io.netty:netty-handler-ssl-ocsp (Maven): affected from 4.2.0.Final; fixed in 4.2.16.Final\n- io.netty:netty-handler-ssl-ocsp (Maven): affected from 4.2.0.Final; fixed in 4.2.16.Final\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-56821/ (Markdown: https://insights.sbomify.com/CVE-2026-56821/index.md)","id":"CVE-2026-56821","markdown":"https://insights.sbomify.com/CVE-2026-56821/index.md","name":"CVE-2026-56821","record":{"aliases":["CLEANSTART-2026-PX19443","CLEANSTART-2026-ZL96278","DEBIAN-CVE-2026-56821","ECHO-ff9e-bb84-4e6f","GHSA-g7hg-vrcf-mvmr","MINI-263c-frj3-4m39","MINI-6v6p-qw2p-fh4j","MINI-7m24-8f7v-j7q5","MINI-8jc3-54wc-w96q","MINI-9x2m-6575-8gxr","MINI-c527-2fg8-4f33","MINI-f625-frpw-cv28","MINI-q45f-2w84-7rxr","MINI-r37f-q2f9-2765","MINI-w47h-frvp-vpwm","UBUNTU-CVE-2026-56821"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Java network framework","requires_auth":"none","summary":"An on-path attacker can bypass certificate revocation checks by replaying expired OCSP responses, allowing revoked certificates to be accepted.","user_interaction":"not_required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"netty","vendor":"netty"}],"cvss":{"score":7.4,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-299","name":"Improper Check for Certificate Revocation"}],"description":"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.","ecosystems":["Maven"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator","id":"CVE-2026-56821","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Maven","product":"netty:netty","products":["netty:netty"],"type":"security_feature_bypass","year":"2026"},"n_packages":4,"n_references":1,"next":{"headline":"Netty: TOCTOU in OcspServerCertificateValidator","id":"CVE-2026-56822"},"packages":[{"ecosystem":"Maven","fixed":["4.1.136.Final"],"introduced":["0"],"last_affected":[],"package":"io.netty:netty-handler-ssl-ocsp","purl":null,"source":"GHSA-g7hg-vrcf-mvmr"},{"ecosystem":"Maven","fixed":["4.1.136.Final"],"introduced":["0"],"last_affected":[],"package":"io.netty:netty-handler-ssl-ocsp","purl":"pkg:maven/io.netty/netty-handler-ssl-ocsp","source":"GHSA-g7hg-vrcf-mvmr"},{"ecosystem":"Maven","fixed":["4.2.16.Final"],"introduced":["4.2.0.Final"],"last_affected":[],"package":"io.netty:netty-handler-ssl-ocsp","purl":null,"source":"GHSA-g7hg-vrcf-mvmr"},{"ecosystem":"Maven","fixed":["4.2.16.Final"],"introduced":["4.2.0.Final"],"last_affected":[],"package":"io.netty:netty-handler-ssl-ocsp","purl":"pkg:maven/io.netty/netty-handler-ssl-ocsp","source":"GHSA-g7hg-vrcf-mvmr"}],"prev":{"headline":"Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks","id":"CVE-2026-56820"},"products":["netty"],"published":"2026-07-28","related":[{"cvss_score":9.1,"headline":"Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext","id":"CVE-2026-75595","kev_date_added":null,"published":"2026-08-19"},{"cvss_score":8.7,"headline":"Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing","id":"CVE-2026-75596","kev_date_added":null,"published":"2026-08-19"},{"cvss_score":8.7,"headline":"Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang","id":"CVE-2026-59901","kev_date_added":null,"published":"2026-07-29"},{"cvss_score":8.7,"headline":"Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion","id":"CVE-2026-55851","kev_date_added":null,"published":"2026-07-21"},{"cvss_score":8.7,"headline":"Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion","id":"CVE-2026-56745","kev_date_added":null,"published":"2026-07-21"},{"cvss_score":8.7,"headline":"Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records","id":"CVE-2026-45674","kev_date_added":null,"published":"2026-06-12"},{"cvss_score":8.7,"headline":"Netty has Insufficient Bailiwick Validation for NS Records","id":"CVE-2026-47691","kev_date_added":null,"published":"2026-06-12"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-07-31","vendors":["netty"]},"summary":"An on-path attacker can bypass certificate revocation checks by replaying expired OCSP responses, allowing revoked certificates to be accepted.","url":"https://insights.sbomify.com/CVE-2026-56821/"}