Security readout for executives and security teams
Plain-English summary
A flaw in the Netty networking library's HAProxy protocol decoder lets a remote attacker send a malformed message that leaks memory on the server. Repeated abuse can exhaust resources and crash applications that trust upstream proxy headers, disrupting availability of services built on Netty.
Executive priority
Treat as a high-priority patch cycle for internet-facing or partner-facing services that speak PROXY protocol v2. Not a fire drill: no known exploitation and impact is availability only, but the fix is well-defined and vendor advisories are already flowing.
Technical view
In netty-codec-haproxy before 4.1.135.Final and 4.2.15.Final, HAProxyMessage.readNextTLV() retains a slice of the pooled cumulation buffer before reading the client and verify fields of a PP2_TYPE_SSL TLV. A TLV length under 5 triggers IndexOutOfBoundsException, which HAProxyMessageDecoder does not catch, so the retained slice is never released. Repeated crafted frames drive a memory leak and availability loss.
Likely exposure
Any service using netty-codec-haproxy to terminate or parse PROXY protocol v2 with SSL TLVs from an upstream load balancer or peer. Exposure widens if the PROXY-speaking endpoint is reachable by untrusted clients or if upstream proxies do not sanitize TLV lengths.
Exploitation context
Not listed in CISA KEV and no public reports of active exploitation are cited in the bundle. CVSS 3.1 base 7.5 (AV:N/AC:L/PR:N/UI:N/A:H) reflects a network-reachable, unauthenticated availability impact. Red Hat has issued multiple vendor advisories (RHSA-2026:26017/26018/26586/34608/36820/37390), indicating meaningful downstream reach.
Researcher notes
Root cause is missing release of a retainedSlice when readByte/readInt overrun a short PP2_TYPE_SSL TLV; HAProxyMessageDecoder only catches HAProxyProtocolException, letting IndexOutOfBoundsException escape with the slice still held. CWE-703 and CWE-805 apply. Confirm reachability of the HAProxyMessageDecoder in your pipeline before prioritizing; services that do not enable PROXY protocol are not affected.
Mitigation direction
- Upgrade netty-codec-haproxy to 4.1.135.Final or 4.2.15.Final across all services and container images.
- Apply Red Hat RHSA-2026:26017, 26018, 26586, 34608, 36820, and 37390 to affected platforms.
- Restrict PROXY protocol endpoints so only trusted load balancers can send PP2 TLVs.
- Consult vendor advisories for downstream products that embed Netty until first-party fixes ship.
- Add capacity and memory alerts on Netty-based services to catch leak-driven degradation early.
Validation and detection
- Inventory Java services and dependencies for netty-codec-haproxy versions using SCA or dependency scans.
- Confirm upgraded builds resolve to 4.1.135.Final or 4.2.15.Final and redeploy.
- Verify Red Hat patched RPMs are installed on affected RHEL and middleware hosts.
- Review network policy to ensure PROXY protocol listeners are not exposed to untrusted networks.
- Monitor direct memory and pooled buffer metrics after deploy to confirm no residual leak.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-703: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-805: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-44893 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GitHub_MCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-06-12T15:01:18.066Z: Reported to Red Hat.
- 2026-06-12T14:00:25.801Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/netty/netty/security/advisories/GHSA-cc37-9q2j-3hfvCVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/netty/netty/releases/tag/netty-4.1.135.FinalCVE reference, GitHub_M · x_refsource_MISC
- https://github.com/netty/netty/releases/tag/netty-4.2.15.FinalCVE reference, GitHub_M · x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-44893CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2488383CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44893.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:26586CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:36820CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:37390CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:26018CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:26017CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:34608CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Check or Handling of Exceptional Conditions
Improper Check or Handling of Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Buffer Access with Incorrect Length Value
Buffer Access with Incorrect Length Value represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.