CVE-2009-1891

7.1 HIGH 17% exploit odds Fix listed Denial of service Library

What it is

The mod_deflate module in Apache httpd 2.2.11 and earlier compresses large files until completion even after the associated network connection is closed, which allows remote attackers to cause a denial of service (CPU consumption).

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 17.1% chance of exploitation in the next 30 days (EPSS). Higher than most.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2009-07-10 15:30 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-16 23:08 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 17.1% in the next 30 days (EPSS).
Severity: 7.1 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2009-07-10 15:30 UTC
Last modified: 2026-06-16 23:08 UTC
Exploit probability: 17.1% · EPSS, next 30 days
Weakness: CWE-400 · Uncontrolled resource consumption
Record status: Modified

Affected

Apache Http Server < 2.0.64
Apache Http Server < 2.2.12
Debian Linux 4.0
Debian Linux 5.0
Debian Linux 6.0
Fedoraproject Fedora 11
Canonical Ubuntu Linux 6.06
Canonical Ubuntu Linux 8.04

Attack profile CVSS 2.0 · 7.1

Attack vector: Network
Complexity: Medium
Authentication: None
Confidentiality: None
Integrity: None
Availability: Complete

Raw vector

AV:N/AC:M/Au:N/C:N/I:N/A:C

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2009-1891.md and follow it. Check whether this project is affected by CVE-2009-1891. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record