CVE-2026-56821— Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator
Possible ATT&CK Techniques 1AI
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I. Basic Information for CVE-2026-56821
Vulnerability Information
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Vulnerability Title
Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator
Source: CVE Program / CVE List V5
Vulnerability 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 Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
证书撤销验证不恰当
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-56821
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POCPremium
Qwen3.6-35B-A3B · 12257 chars
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III. Intelligence Information for CVE-2026-56821
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Vendor Advisories for CVE-2026-56821 (1)
Same Patch Batch · netty · 2026-07-28 · 3 CVEs total
| CVE-2026-56822 | 7.4 HIGH | Netty: TOCTOU in OcspServerCertificateValidator |
| CVE-2026-59921 | 5.7 MEDIUM | Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder |
IV. Related Vulnerabilities
Same product: netty
- CVE-2026-59898
Netty: WebSockets V07/V08 handshaker missing Connection/Upgr - CVE-2026-59899
Netty HttpContentEncoder: Unbounded Per-Connection Queue Gro - CVE-2026-59900
Netty codec-http2: Lack of Host Header Deduplication in HTTP - CVE-2026-59901
Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads - CVE-2026-59919
Netty: HAProxy V1 Protocol CRLF Injection via AF_UNIX Addres
Same vendor: netty
- CVE-2026-59898
Netty: WebSockets V07/V08 handshaker missing Connection/Upgr - CVE-2026-59899
Netty HttpContentEncoder: Unbounded Per-Connection Queue Gro - CVE-2026-59900
Netty codec-http2: Lack of Host Header Deduplication in HTTP - CVE-2026-59901
Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads - CVE-2026-59919
Netty: HAProxy V1 Protocol CRLF Injection via AF_UNIX Addres
Same weakness: CWE-299
- CVE-2026-9636
Rockwell Automation CompactLogix® 5380 ControlLogix® 5580 / - CVE-2026-6899
Improper Check for Certificate Revocation in S2OPC - CVE-2026-4428
CRL Distribution Point Scope Check Logic Error in AWS-LC - CVE-2025-11955
Incorrect validation of OCSP certificates in TheGreenBow VPN - CVE-2025-36057
IBM Cognos Analytics Mobile (iOS) authentication bypass
V. Comments for CVE-2026-56821
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