CVE-2026-56820General(netty / netty)

LOWCVSS 9.1 · CRITICAL

Signal is active with 1 mentions in latest observed window

Immediate actions

Patch netty netty systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and prior to 4.1.135.Final, `OcspClient` does not validate that the `CertificateID` in an OCSP response matches the requested `CertificateID`, which can lead to replay attack. `OcspClient.validateResponse` accepts a legitimately signed `GOOD` status response for an unrelated certificate issued by the same CA, allowing bypass of revocation checks for another certificate. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

netty CVEs Back to dashboard

0.5/ 10 priority

Sources & remediation

Patch / fix

Exploit / PoC references

https://github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg

Other references

Weakness type (CWE)

CWE-295

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

netty

Threat summary

Patch or workaround signal is available
4 mentions across 3 observed days
Momentum state: stable

What's happening

Patch or workaround mentioned in 1 signal
Technical details provided in 3 signals
General: 2 classified signals
Disclosure: 1 classified signal
Peaked 2d ago at 2 mentions (2026-07-21); latest day: 1
4 total mentions across 3 days

Affected systems

Vendors

netty

Products

netty

Deep dive

Activity timeline4 mentions / 3d

Signal classification3 categories

General

250.0%

Disclosure

125.0%

Patch

125.0%

Referenced assets6 URLs

By indicator

Classification over time

Date	Total	Labels

2026-07-21	2	General2
2026-07-22	1	Disclosure1
2026-07-27	1	Patch1

Full discourse4 posts

DFIR Lab@DFIR_Lab86d
Patch
🚨 HIGH: CVE-2026-56820 (CVSS 7.4) affects Netty framework v4.2.0-4.2.15 & pre-4.1.135. OcspClient fails to validate CertificateID in OCSP responses, enabling replay attacks to bypass revocation checks. Patch to 4.1.136+ or 4.2.16+ immediately. #CVE #PatchNow https://t.co/ZTPTA0gDtn
Post summary
The tweet announces CVE-2026-56820 affecting Netty with a CVSS score of 7.4, notes that a replay attack via OCSP responses is possible, and urges users to patch to 4.1.136+ or 4.2.16+; no active exploitation or PoC is mentioned.
0000030
96 followersView on X
Vulmon Vulnerability Feed@VulmonFeeds91d
Disclosure
CVE-2026-56820 OCSP Response Validation Bypass in Netty 4.1 and 4.2 Versions https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-56820
Post summary
The post announces CVE-2026-56820 as an OCSP response validation bypass in Netty 4.1 and 4.2, without mentioning any proof of concept, exploit, patch, or active exploitation.
0000074
4.1K followersView on X
Infoflowcloud@infoflowcloud91d
General
🚨*CVE* CVE-2026-56820 Netty is a network application framework for development of protocol servers and clients. In versions http://4.2.0.Final through http://4.2.15.Final and prior to http://4.1.135.Final, `Oc… https://www.cve.org/CVERecord?id=CVE-2026-56820 ---… http://infoflow.cloud`
Post summary
The post references CVE-2026-56820 for Netty, listing affected versions and linking to the CVE record and an external site, but provides no exploit, patch, or technical detail.
0000032
94 followersView on X
CVE@CVEnew91d
General
CVE-2026-56820 Netty is a network application framework for development of protocol servers and clients. In versions http://4.2.0.Final through http://4.2.15.Final and prior to http://4.1.135.Final, `Oc… https://www.cve.org/CVERecord?id=CVE-2026-56820
Post summary
The post references CVE-2026-56820 with a list of affected Netty versions but offers no details on exploitation, fixes, or mitigation.
000001.1K
57.8K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	netty	netty	-	-	-

Explore more

Back to dashboard netty CVEs netty vulnerabilities

What researchers are saying

CVE-2026-56820

DFIR Lab[verified]@DFIR_LabPatch

The tweet announces CVE-2026-56820 affecting Netty with a CVSS score of 7.4, notes that a replay attack via OCSP responses is possible, and urges users to patch to 4.1.136+ or 4.2.16+; no active exploitation or PoC is mentioned.

Vulmon Vulnerability Feed@VulmonFeedsDisclosure

The post announces CVE-2026-56820 as an OCSP response validation bypass in Netty 4.1 and 4.2, without mentioning any proof of concept, exploit, patch, or active exploitation.

Infoflowcloud@infoflowcloudGeneral

The post references CVE-2026-56820 for Netty, listing affected versions and linking to the CVE record and an external site, but provides no exploit, patch, or technical detail.

CVE@CVEnewGeneral

The post references CVE-2026-56820 with a list of affected Netty versions but offers no details on exploitation, fixes, or mitigation.