How severe is CVE-2011-1398?

CVE-2011-1398 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2011-1398 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-1398?

CVE-2011-1398 primarily affects Php. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-1398?

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

When was CVE-2011-1398 published?

CVE-2011-1398 was published on 2012-08-30 and last updated on 2026-06-16.

CVE-2011-1398

CVE-2011-1398 is a medium-severity vulnerability in Php with a CVSS 2.0 base score of 4.3. Its EPSS exploit-prediction score of 10% places it in the 95th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 2.0 base score 4.3)
EPSS exploit prediction: 10% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Php
Published: 2012-08-30
Last modified: 2026-06-16

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.

Frequently asked questions

What is CVE-2011-1398?: 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.
How severe is CVE-2011-1398?: CVE-2011-1398 has a CVSS 2.0 base score of 4.3, rated medium severity.
Is CVE-2011-1398 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-1398?: CVE-2011-1398 primarily affects Php. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2011-1398?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2011-1398 published?: CVE-2011-1398 was published on 2012-08-30 and last updated on 2026-06-16.

References

Affected products (11)

cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.0:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.1:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.2:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.3:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.4:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.5:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.6:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.7:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.8:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.3.9:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

221.161.235.168 (ipv4-addr)
187.141.71.166 (ipv4-addr)
103.20.122.54 (ipv4-addr)
82.199.197.245 (ipv4-addr)
58.221.244.34 (ipv4-addr)
222.99.52.202 (ipv4-addr)
220.88.220.59 (ipv4-addr)
211.253.10.61 (ipv4-addr)