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Vulnerabilities

Vulnerability · CVE-2001-1556

The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers…

Published Dec 31, 2001 · catalog updated Jun 16, 2026 · http server

Last checked Nov 4, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2001-1556. EPSS is 3.56%. Act only if a listed version of http server is installed.

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
Medium5.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
3.56%
Remediation
Version ranges on file
Affected products
cpe apache/http server

The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.

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< 1.3.31
  • cpe apache/http server< 2.0.49

How to fix CVE-2001-1556

What to do

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

Should you patch?

No confirmed exploitation is on record for CVE-2001-1556. EPSS is 3.56%. Act only if a listed version of http server is installed.

Which versions are affected?

Compare what you have installed with apache/http server < 1.3.31; apache/http server < 2.0.49. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-532: Insertion of Sensitive Information into Log File. EPSS 3.56%. 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. Dec 31, 2001 · Monitored products — critical

    Detected

    The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.

  2. Jun 16, 2026 · Monitored products — critical

    Updated

    The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.

Sources

  • CVE.orgVulnerability recordCVE-2001-1556

    Official CVE identifier

    cve.org
  • Monitored products — criticalVendor advisoryCVE-2001-1556

    The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 3, 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 3, 2026