Is CVE-2011-1398 in the CISA KEV catalog?

No. CVE-2011-1398 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2011-1398?

CVE-2011-1398 has a CVSS v2 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2011-1398?

CVE-2011-1398 has an EPSS score of 10.17% (95th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2011-1398

MEDIUMEPSS 95th pctl

4.3

CVSS v2

NVD

Description

The sapi_header_op function in main/SAPI.c in PHP before 5.3.11 and 5.4.x before 5.4.0RC2 does not check for %0D sequences (aka carriage return characters), which allows remote attackers to bypass an HTTP response-splitting protection mechanism via a crafted URL, related to improper interaction between the PHP header function and certain browsers, as demonstrated by Internet Explorer and Google Chrome.

CWE-20Improper Input Validation

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

10.17%probability of exploitation in 30 days

95thpercentile

Very high risk: more likely to be exploited than 95% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-29.