# CVE-2026-87776: compression vulnerable to Denial of Service via memory leak on premature response close

> A remote attacker can crash the server by repeatedly aborting compressed connections, causing a memory leak in the compression middleware.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 11 Sep 2026
- **Also known as:** AZL-101778, CLEANSTART-2026-IQ33916, CLEANSTART-2026-WT34864, CLSA-2026-1791278863, CLSA-2026-1792473493, CLSA-2026-1792473778, CLSA-2026-1792489791, CLSA-2026-1792490254, DEBIAN-CVE-2026-87776, ECHO-abd4-2c76-3d12, GHSA-vc2v-76pw-4v95, MINI-2232-g2fg-vw22, MINI-2924-3363-jv5v, MINI-29v5-67qv-45f3, MINI-3wcf-hxfq-9cc7, MINI-gvvc-j52w-ccf8, MINI-hf27-vjmr-3phj, MINI-jq39-c438-hh8w, MINI-mcr7-hhqx-6pxq, MINI-mh6j-rw82-2cjf, MINI-v6xq-wq69-43vg, MINI-w77f-6226-q26r, ROOT-APP-NPM-CVE-2026-87776, UBUNTU-CVE-2026-87776

## What is CVE-2026-87776?

CVE-2026-87776 is a high-severity denial of service vulnerability in compression, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

compression is a Node.js and Express compression middleware. In versions before 1.8.2, when a client aborts the connection while a compressed response is still being sent, the zlib stream created to compress that response is never destroyed, so each aborted compressed response leaks its native zlib memory. A remote unauthenticated attacker can repeatedly open requests and disconnect early, exhausting the available memory and crashing the server. All applications using compression are affected. The issue is fixed in compression 1.8.2, and users should upgrade to 1.8.2 or later.

Weakness: CWE-459 (Incomplete Cleanup), CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-87776?

2 open source packages ship an affected version, including compression.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `compression` | npm | All versions | 1.8.2 |
| `compression` | npm | All versions | 1.8.2 |

## How do I fix CVE-2026-87776?

Upgrade compression to 1.8.2 or later.

## Is CVE-2026-87776 being exploited?

There is no known exploitation of CVE-2026-87776 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87776 and fix it if it is affected.

What it is: CVE-2026-87776 is a high-severity denial of service vulnerability in compression, published on 11 Sep 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-2026-87776 in the wild and no public exploit code.

Affected packages and fixed versions:
- compression (npm): affected all versions; fixed in 1.8.2
- compression (npm): affected all versions; fixed in 1.8.2

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-2026-87776/ (Markdown: https://insights.sbomify.com/CVE-2026-87776/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87776
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87776
- OSV: https://osv.dev/vulnerability/CVE-2026-87776

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87776/
Summaries are generated and may contain mistakes; the official description above is the record.