# CVE-2026-48043: netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion > A remote attacker can cause memory exhaustion and JVM crash in Netty HTTP/2 servers by triggering a ByteBuf reference-count leak during decompression. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`) - **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-BV89679, CLEANSTART-2026-GU85680, CLEANSTART-2026-HW37791, CLEANSTART-2026-VG66831, CLEANSTART-2026-VM89783, CLSA-2026-1786361708, CLSA-2026-1786362389, DEBIAN-CVE-2026-48043, ECHO-b4ed-b9f0-91a0, GHSA-c2gf-v879-257j, MINI-24qg-7grm-795q, MINI-2c52-84cf-2frr, MINI-2crq-5wr7-j6rc, MINI-2v86-6mwq-qj5h, MINI-2wmm-4xx2-39mh, MINI-34rp-cfrg-9w6h, MINI-3fgm-5369-9j5x, MINI-3p9p-97xq-2p86, MINI-3vpq-2pgj-hccx, MINI-4gfm-qcq7-96w4, MINI-4rcr-2mvc-h876, MINI-57m6-w5c4-9frr, MINI-5jrg-5h5v-wjv7, MINI-63hr-p84g-c7pq, MINI-68v9-vwx6-5qf3, MINI-6q8m-88qh-w48x, MINI-6wgq-8xvj-2jc5, MINI-77hh-56q6-2628, MINI-77vx-jx8w-x5f7, MINI-7f9j-hpwg-qf3w, MINI-7mcj-f87c-qmm6, MINI-8q4v-wfqw-wmqm, MINI-8q9q-gv7v-qp6c, MINI-8r5r-78x2-m2j9, MINI-9454-f86j-p2rc, MINI-97v7-7rjf-7fqh, MINI-9q2w-jh2r-8mr3, MINI-c3wh-3fqq-xj2m, MINI-c5cg-cx46-qfg3, MINI-c8cf-7gxv-hgc2, MINI-cc22-4xvq-f3vf, MINI-cg89-vh7h-v25h, MINI-cxwx-h3pr-pq4j, MINI-f4g4-74hj-gcf5, MINI-f534-cvgc-hcx9, MINI-fc66-7q3f-9g85, MINI-fvc3-29qw-4h6c, MINI-fwrf-4h7v-8fv8, MINI-fx73-m9g6-hcrf, MINI-g2qp-53rp-2w65, MINI-gc5x-66x7-xgmc, MINI-gjh8-vrm2-8vvj, MINI-gmvv-5hhx-g827, MINI-h3qh-vx4g-xx42, MINI-hm4h-vqg6-q3g5, MINI-hq2p-6hxc-wppg, MINI-j352-vwcg-2wqh, MINI-jpv5-j4vx-x2wc, MINI-jvwj-pmrm-pxhw, MINI-m3r8-f6hx-8phj, MINI-mq3c-x397-6cq5, MINI-p7r2-85pm-457m, MINI-pc5q-m32m-xhh6, MINI-pgg6-q9cm-w89f, MINI-q2c3-5cr2-g6q7, MINI-q7f4-5gg6-75rw, MINI-q874-v444-7jgq, MINI-qj9m-r37m-p257, MINI-rm7g-qxr8-r553, MINI-vgx5-v4m2-6rpm, MINI-vrrm-4w32-mpjf, MINI-w4mg-547j-2739, MINI-w898-cmvm-2f24, MINI-wv68-c4w9-cvjv, MINI-wwfh-67vp-mgrh, MINI-x822-jgpx-x88x, MINI-x8cv-283p-6g5p, MINI-x9vr-v7g7-6f7q, MINI-xc7c-gg9m-wp3g, MINI-xr72-4jxm-mg5j, MINI-xrc2-qrjc-q264, MINI-xrr2-g973-33q6, MINI-xx9f-g688-p765, MINI-xxg9-5333-p269, ROOT-APP-MAVEN-CVE-2026-48043, UBUNTU-CVE-2026-48043 ## What is CVE-2026-48043? CVE-2026-48043 is a medium-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. In netty-codec-http2 prior to versions 4.1.135.Final and 4.2.15.Final, the `DelegatingDecompressorFrameListener` class orchestrates HTTP/2 decompression by embedding a per-stream `EmbeddedChannel` that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled `ByteBuf` handed to an anonymous `ChannelInboundHandlerAdapter` tail handler, which becomes the sole owner responsible for releasing it. A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME. Versions 4.1.135.Final and 4.2.15.Final patch the issue. Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime), CWE-401 (Missing Release of Memory after Effective Lifetime), CWE-400 (Uncontrolled Resource Consumption) ## Which versions are affected by CVE-2026-48043? 4 open source packages ship an affected version, including io.netty:netty-codec-http2. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `io.netty:netty-codec-http2` | Maven | All versions | 4.1.135.Final | | `io.netty:netty-codec-http2` | Maven | All versions | 4.1.135.Final | | `io.netty:netty-codec-http2` | Maven | From 4.2.0.Alpha1 | 4.2.15.Final | | `io.netty:netty-codec-http2` | Maven | From 4.2.0.Alpha1 | 4.2.15.Final | Products: Netty Netty. ## How do I fix CVE-2026-48043? Upgrade io.netty:netty-codec-http2 to a fixed version for your release line: 4.1.135.Final or 4.2.15.Final. ## Is CVE-2026-48043 being exploited? There is no known exploitation of CVE-2026-48043 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-2026-48043 and fix it if it is affected. What it is: CVE-2026-48043 is a medium-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-2026-48043 in the wild and no public exploit code. Affected packages and fixed versions: - io.netty:netty-codec-http2 (Maven): affected all versions; fixed in 4.1.135.Final - io.netty:netty-codec-http2 (Maven): affected all versions; fixed in 4.1.135.Final - io.netty:netty-codec-http2 (Maven): affected from 4.2.0.Alpha1; fixed in 4.2.15.Final - io.netty:netty-codec-http2 (Maven): affected from 4.2.0.Alpha1; 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-2026-48043/ (Markdown: https://insights.sbomify.com/CVE-2026-48043/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48043 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48043 - OSV: https://osv.dev/vulnerability/CVE-2026-48043 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-48043/ Summaries are generated and may contain mistakes; the official description above is the record.