CVE-2026-56819

Atlassian heeft kwetsbaarheden verholpen in diverse producten zoals Bamboo, Bitbucket, Confluence, Jira, Crowd en Fisheye. De kwetsbaarheden bevinden zich in diverse Third-Party producten waar eerder updates voor zijn verschenen. Atlassian heeft deze updates verwerkt in de eigen producten.

Ein Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Sicherheitsprüfungen zu umgehen, Anfragen oder Header zu manipulieren, Zertifikatsprüfungen zu unterlaufen sowie einen Denial of Service zu verursachen.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Atlassian Bitbucket, Atlassian Confluence, Atlassian Crucible, Atlassian Fisheye und Atlassian Jira ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen, und um Sicherheitsvorkehrungen zu umgehen.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Bitbucket, Confluence, Fisheye/Crucible, Jira Software und Jira Service Management ausnutzen, um beliebigen Programmcode auszuführen, Sicherheitsmaßnahmen zu umgehen, serverseitige Request-Forgery-Angriffe (SSRF) durchzuführen, Cross-Site-Scripting-Angriffe zu starten, sensible Informationen offenzulegen, Daten zu manipulieren oder Denial-of-Service-Zustände herbeizuführen.

### Summary A remote, unauthenticated peer can leak one direct `ByteBuf` per HTTP/2 `DATA` frame in applications that enable HTTP/2 content decompression via `DelegatingDecompressorFrameListener`. When a `DATA` frame is processed for a stream whose decompressor has already been closed, `Http2Decompressor.decompress(...)` retains the frame buffer but never releases it on the error path, so its reference count never returns to zero. Repeating this over a long-lived HTTP/2 connection exhausts direct memory and crashes the JVM with `OutOfMemoryError` — a denial of service. ### Details In `codec-http2/src/main/java/io/netty/handler/codec/http2/DelegatingDecompressorFrameListener.java`, `Http2Decompressor.decompress(...)` does: ```java // around line 433 decompressor.writeInbound(data.retain()); ``` The argument `data.retain()` is evaluated **before** `writeInbound(...)` executes, incrementing the buffer's reference count (`refCnt: 1 -> 2`). The very first statement of `EmbeddedChannel.writeInbound(...)` is `ensureOpen()` (`EmbeddedChannel.java:360`), which throws `ClosedChannelException` when the decompressor's internal `EmbeddedChannel` has already been closed. When that happens: - the `DATA` payload has been `retain()`ed but never entered the pipeline, so the decoder's `finally { release() }` never runs; - the surrounding `catch (Throwable t)` block in `decompress(...)` (around line 451) does **not** release the extra reference; - the input buffer therefore can never reach refCnt 0, and its (typically direct) memory is leaked. The decompressor channel is closed on a reachable path: `Http2Connection` `onStreamRemoved` → `Http2Decompressor.cleanup()` → `EmbeddedChannel.finishAndReleaseAll()` (`DelegatingDecompressorFrameListener.java:125-133` and `418-420`). A peer that sends `DATA` frames for a stream whose decompressor has already been cleaned up (e.g. continuing to send `DATA` after `END_STREAM` / stream removal) thus leaks one direct `ByteBuf` per frame. **Affected code**: `DelegatingDecompressorFrameListener.java`, method `Http2Decompressor.decompress(...)` — the `decompressor.writeInbound(data.retain())` call (line ~433) and its `catch (Throwable t)` block (line ~451), which lacks a `data.release()` rollback. **Suggested fix**: track whether `writeInbound` succeeded and roll back the extra `retain()` only when the data never entered the pipeline: ```java boolean writeSucceeded = false; try { decompressor.writeInbound(data.retain()); writeSucceeded = true; // pipeline now owns the release if (endOfStream) { decompressor.finish(); } return 0; } catch (Throwable t) { if (!writeSucceeded) { data.release(); // roll back the extra retain(); data never entered pipeline } if (t instanceof Http2Exception) { throw (Http2Exception) t; } throw streamError(stream.id(), INTERNAL_ERROR, t, ...); } ``` | Case | writeSucceeded | catch action | Reason | |------|:---:|---|---| | `ensureOpen()` throws (this bug) | `false` | `data.release()` | data never entered pipeline | | handler throws internally | `true` | no release | decoder `finally` already released | | `finish()` throws | `true` | no release | `writeInbound` already succeeded | ### PoC Reproduced against the official, unmodified `netty-codec-http2-4.2.15.Final.jar` from Maven Central, using real netty classes and measuring `ByteBuf.refCnt()` directly (the leaking logic is not mocked). Reproduction steps: 1. Download the official artifacts and their dependencies from Maven Central (version `4.2.15.Final`): `netty-common`, `netty-buffer`, `netty-transport`, `netty-resolver`, `netty-handler`, `netty-codec-base`, `netty-codec`, `netty-codec-http`, `netty-codec-http2`, `netty-codec-compression`. 2. Build a real `Http2Decompressor` wrapping a real gzip decoder `EmbeddedChannel` (`ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP)`). 3. Close the internal decompressor channel (equivalent to the end state of `cleanup()` / `finishAndReleaseAll()`). 4. Encode a real gzip `DATA` payload with `ZlibCodecFactory.newZlibEncoder(GZIP)` (`refCnt = 1`). 5. Call `decompress(...)` on the closed channel. 6. Observe: `writeInbound(...)` throws `ClosedChannelException` at its `ensureOpen()` entry (`EmbeddedChannel.java:360`), reached from `DelegatingDecompressorFrameListener.java:433`; `data.refCnt()` is now `2`. 7. Release once as the frame reader would; `refCnt` stays at `1` (`release()` returns `false`) → leaked. Observed reference-count trace: ``` gzipData initial refCnt = 1 decompress -> data.retain() -> refCnt = 2 (retain applied, never rolled back) caller releases once -> refCnt = 1 (release() returns false; not deallocated) => buffer never reaches 0 -> direct memory leaked ``` Observed exception stack (confirms the leak point): ``` java.nio.channels.ClosedChannelException at io.netty.channel.embedded.EmbeddedChannel.checkOpen(EmbeddedChannel.java:959) at io.netty.channel.embedded.EmbeddedChannel.ensureOpen(EmbeddedChannel.java:979) at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:360) at io.netty.handler.codec.http2.DelegatingDecompressorFrameListener$Http2Decompressor .decompress(DelegatingDecompressorFrameListener.java:433) ``` Two notes on the harness (they do not affect the leak mechanism): - The internal channel is closed directly via `close()` rather than through `cleanup()`. The end state is identical (channel closed → `writeInbound` throws at `ensureOpen()`); the bug depends on "channel closed → retain not rolled back", not on *how* the channel was closed. - In the isolated harness the rethrown `StreamException`'s root cause shows as `NullPointerException` because the harness does not initialise an `Http2LocalFlowController` (a secondary exception reported during channel close). The leak is already sealed at the `ClosedChannelException` thrown by `writeInbound`'s `ensureOpen()` (line 360); in a real server with the flow controller initialised, the triggering exception is the `ClosedChannelException` itself. A complete self-contained PoC (`Verify02DecompressLeak.java`, ~150 lines, no test framework) plus the exact `javac` / `java` commands can be attached on request. ### Impact - **Vulnerability type**: uncontrolled resource consumption / memory leak (CWE-401), leading to denial of service. Each crafted `DATA` frame leaks one (typically direct/off-heap) `ByteBuf`. - **Who is impacted**: any server (or client) that enables HTTP/2 content decompression by installing `DelegatingDecompressorFrameListener` in its HTTP/2 pipeline. - **Attacker requirements**: remote, unauthenticated. The attacker only needs to send HTTP/2 `DATA` frames for a stream whose decompressor has been cleaned up (e.g. continue sending `DATA` after `END_STREAM`). No special server configuration beyond decompression being enabled. - **Result**: sustained triggering over a long-lived connection exhausts direct memory and crashes the JVM with `OutOfMemoryError`.