ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2009-1891

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…

Published Jul 10, 2009 · catalog updated Jun 16, 2026 · http server

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check this week

CVE-2009-1891 is not in CISA KEV. FIRST estimates a 17.11% chance of exploitation in the next 30 days. Check whether you run http server.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
17.11%
Remediation
Version ranges on file
Affected products
cpe apache/http server · cpe canonical/ubuntu linux · cpe debian/debian linux

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).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apache/http server< 2.0.64
  • cpe apache/http server< 2.2.12
  • cpe canonical/ubuntu linux6.06
  • cpe debian/debian linux4.0
  • cpe debian/debian linux5.0
  • cpe debian/debian linux6.0

How to fix CVE-2009-1891

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2009-1891 is not in CISA KEV. FIRST estimates a 17.11% chance of exploitation in the next 30 days. Check whether you run http server.

Which versions are affected?

Compare what you have installed with apache/http server < 2.0.64; apache/http server < 2.2.12; canonical/ubuntu linux 6.06; debian/debian linux 4.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption. EPSS 17.11%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Apache HTTP Server security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jul 10, 2009 · Monitored products — critical

    Detected

    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).

  2. Jun 16, 2026 · Monitored products — critical

    Updated

    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).

Sources

  • CVE.orgVulnerability recordCVE-2009-1891

    Official CVE identifier

    cve.org
  • Monitored products — criticalVendor advisoryCVE-2009-1891

    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).

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — criticalNov 4, 2026