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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-09-16
• Weakness: CWE-401

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.

Affected products

• Npm Compression: before 1.8.2 — fixed in 1.8.2
• compression: before 1.8.2 — fixed in 1.8.2

How to fix

Upgrade to a fixed version: Npm Compression 1.8.2; compression 1.8.2. Check the vendor advisory for mitigations.

References

• https://cna.openjsf.org/security-advisories.html
• https://github.com/expressjs/compression/security/advisories/GHSA-vc2v-76pw-4v95

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