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high · CVSS 7.5

CVE-2026-93564

Io.netty/netty-codec-haproxy: netty: haproxy proxy-v2 nested-tlv grandchild bytebuf reference-count leak (incomplete fix of pr #16881)

Published 18 Sept 2026 · Source updated 6 Nov 2026 · Retrieved 2026-11-06 10:44 UTC

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What happened?

A flaw was found in Netty. A reference-count leak in the HAProxy PROXY-v2 message decoder allows a remote, unauthenticated attacker to send specially crafted PROXY-protocol v2 headers. This can lead to memory exhaustion, resulting in a Denial of Service (DoS) for the affected system.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
SoftwareVersion informationFixed version
io.netty/netty-codec-haproxyRed Hatunaffected: 4.1.138.Final-redhat-00001 to < *See vendor advisory
netty-codec-haproxyRed HatDefault status: unaffectedSee vendor advisory
keycloak-rhel9-containerRed Hatunaffected: 26.4-29 to < *See vendor advisory
keycloak-rhel9-operator-bundle-containerRed Hatunaffected: 26.4.17-2 to < *See vendor advisory
keycloak-rhel9-operator-containerRed Hatunaffected: 26.4-30 to < *See vendor advisory
netty-codec-haproxyRed HatDefault status: unaffectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: unaffectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: unaffectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory
netty-codec-haproxyRed HatDefault status: affectedSee vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

  1. Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
  2. Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
  3. Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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