How severe is CVE-2001-1556?

CVE-2001-1556 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2001-1556 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2001-1556?

CVE-2001-1556 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2001-1556?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2001-1556 published?

CVE-2001-1556 was published on 2001-12-31 and last updated on 2026-06-16.

CVE-2001-1556

CVE-2001-1556 is a medium-severity vulnerability in Apache Http Server with a CVSS 2.0 base score of 5.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-532.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-532
Affected product: Apache Http Server
Published: 2001-12-31
Last modified: 2026-06-16

Description

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.

Frequently asked questions

What is 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 to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.
How severe is CVE-2001-1556?: CVE-2001-1556 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2001-1556 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2001-1556?: CVE-2001-1556 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2001-1556?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2001-1556 published?: CVE-2001-1556 was published on 2001-12-31 and last updated on 2026-06-16.

References

Affected products (1)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

90.160.135.217 (ipv4-addr)
62.36.19.42 (ipv4-addr)
62.36.19.41 (ipv4-addr)