How severe is CVE-2009-1891?

CVE-2009-1891 has a CVSS 2.0 base score of 7.1, rated high severity.

Is CVE-2009-1891 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-1891?

CVE-2009-1891 primarily affects Redhat Enterprise Linux Desktop. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-1891?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2009-1891 published?

CVE-2009-1891 was published on 2009-07-10 and last updated on 2026-06-16.

CVE-2009-1891

CVE-2009-1891 is a high-severity vulnerability in Redhat Enterprise Linux Desktop with a CVSS 2.0 base score of 7.1. Its EPSS exploit-prediction score of 17% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 2.0 base score 7.1)
EPSS exploit prediction: 17% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Redhat Enterprise Linux Desktop
Published: 2009-07-10
Last modified: 2026-06-16

Description

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).

Frequently asked questions

What is 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 remote attackers to cause a denial of service (CPU consumption).
How severe is CVE-2009-1891?: CVE-2009-1891 has a CVSS 2.0 base score of 7.1, rated high severity.
Is CVE-2009-1891 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-1891?: CVE-2009-1891 primarily affects Redhat Enterprise Linux Desktop. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-1891?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2009-1891 published?: CVE-2009-1891 was published on 2009-07-10 and last updated on 2026-06-16.

References

Affected products (14)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:4.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:5.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:6.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:11:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:6.06:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:8.04:*:*:*:-:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:8.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:9.04:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_desktop:5.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_eus:5.3:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server:5.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_aus:5.3:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_workstation:5.0:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

222.99.52.202 (ipv4-addr)
41.224.62.206 (ipv4-addr)
218.4.156.254 (ipv4-addr)
171.100.156.38 (ipv4-addr)