# CVE-2026-48059: Netty HAProxy: Unbalanced Reference Count in Nested PP2_TYPE_SSL TLV Parsing Leads to Memory Exhaustion > Attackers can cause memory exhaustion in Netty HAProxy codec by sending nested SSL TLVs, leading to denial of service. - **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 12 Jun 2026 - **Updated:** 18 Sep 2026 - **Also known as:** CLEANSTART-2026-BD80531, CLEANSTART-2026-HH77101, CLEANSTART-2026-PJ95856, DEBIAN-CVE-2026-48059, ECHO-fd53-f198-b51a, GHSA-h2qv-fj59-j46j, MINI-2848-m34r-9rf8, MINI-2h98-gj5x-j66m, MINI-2q3c-9v8m-xrm3, MINI-37vh-9hvp-xwhr, MINI-6rrw-q4gj-h26r, MINI-73v9-w2mw-2h4f, MINI-785p-64g2-w8wc, MINI-7x74-9942-75h7, MINI-9923-pcfh-vmgh, MINI-9g2j-fmwp-vxrg, MINI-9jxx-43fj-9h6f, MINI-ccjr-92mv-68vw, MINI-fg9g-hq88-4v86, MINI-fw3j-gvr5-q775, MINI-hgm7-6f9r-4678, MINI-hrxh-c9wj-96p8, MINI-jw8m-7wvj-m3jq, MINI-mmv6-p3f4-rrqx, MINI-pxw6-4jr6-3g46, MINI-rrjw-gc3m-w89x, MINI-vwxj-m29j-433q, MINI-w5g5-jcqf-47cv, MINI-w673-c5g4-9vxf, MINI-wg65-59j5-82wx, MINI-ww8j-4h35-j8qf, MINI-x822-66rw-jm66, MINI-xrx9-2q3r-xfc8, MINI-xxxv-m6w5-frcm, UBUNTU-CVE-2026-48059 ## What is CVE-2026-48059? CVE-2026-48059 is a high-severity denial of service vulnerability in Netty Netty, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, the HAProxy PROXY protocol v2 codec in netty leaks native or heap memory on every connection when a client sends a syntactically valid header containing nested `PP2_TYPE_SSL` TLVs (type-length-value records) at depth two or greater. The leak occurs on the successful parse path — no exception is thrown, the message fires downstream, the decoder removes itself, and the application releases the `HAProxyMessage` normally. Yet the underlying cumulation buffer (a pooled, potentially direct `ByteBuf` allocated by the channel) remains permanently pinned. Versions 4.1.135.Final and 4.2.15.Final patch the issue. Weakness: CWE-1286 (Improper Validation of Syntactic Correctness of Input), CWE-401 (Missing Release of Memory after Effective Lifetime) ## Which versions are affected by CVE-2026-48059? 4 open source packages ship an affected version, including io.netty:netty-codec-haproxy. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `io.netty:netty-codec-haproxy` | Maven | All versions | 4.1.135.Final | | `io.netty:netty-codec-haproxy` | Maven | All versions | 4.1.135.Final | | `io.netty:netty-codec-haproxy` | Maven | From 4.2.0.Final | 4.2.15.Final | | `io.netty:netty-codec-haproxy` | Maven | From 4.2.0.Final | 4.2.15.Final | Products: Netty Netty. ## How do I fix CVE-2026-48059? Upgrade io.netty:netty-codec-haproxy to a fixed version for your release line: 4.1.135.Final or 4.2.15.Final. ## Is CVE-2026-48059 being exploited? There is no known exploitation of CVE-2026-48059 in the wild and no public exploit code. ## Other vulnerabilities in Netty Netty - [CVE-2026-75595](https://insights.sbomify.com/CVE-2026-75595/): Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext (critical 9.1) - [CVE-2026-75596](https://insights.sbomify.com/CVE-2026-75596/): Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing (high 8.7) - [CVE-2026-59901](https://insights.sbomify.com/CVE-2026-59901/): Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang (high 8.7) - [CVE-2026-55851](https://insights.sbomify.com/CVE-2026-55851/): Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion (high 8.7) - [CVE-2026-56745](https://insights.sbomify.com/CVE-2026-56745/): Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion (high 8.7) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-48059 and fix it if it is affected. What it is: CVE-2026-48059 is a high-severity denial of service vulnerability in Netty Netty, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-48059 in the wild and no public exploit code. Affected packages and fixed versions: - io.netty:netty-codec-haproxy (Maven): affected all versions; fixed in 4.1.135.Final - io.netty:netty-codec-haproxy (Maven): affected all versions; fixed in 4.1.135.Final - io.netty:netty-codec-haproxy (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final - io.netty:netty-codec-haproxy (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final Task: 1. 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. 2. 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. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-48059/ (Markdown: https://insights.sbomify.com/CVE-2026-48059/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48059 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48059 - OSV: https://osv.dev/vulnerability/CVE-2026-48059 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-48059/ Summaries are generated and may contain mistakes; the official description above is the record.