CVE-2011-1398

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

10.2% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2012-08-30 22:55 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 23:29 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 10.2% in the next 30 days (EPSS).
• Severity: 4.3 MEDIUM (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2012-08-30 22:55 UTC

Last modified

2026-06-16 23:29 UTC

Exploit probability

10.2% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• PHP ≤ 5.3.10
• PHP 5.3.0
• PHP 5.3.1
• PHP 5.3.2
• PHP 5.3.3
• PHP 5.3.4
• PHP 5.3.5
• PHP 5.3.6

Attack profile CVSS 2.0 · 4.3

Attack vector

Network

Complexity

Medium

Authentication

None

Confidentiality

None

Integrity

Partial

Availability

None

Is it in your code?

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