GHSA-xh5x-j8jf-pcpx CVE-2014-0099

Improper Neutralization of CRLF Sequences in HTTP Headers in Apache Tomcat

Medium Maven

Severity: Medium; The publisher's own rating, not a CVSS score
Exploit chance (EPSS): 8.84%; Chance of exploitation in the next 30 days. Higher than 95.20% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
Fix: Available; 2 packages have a fixed version

Description

Integer overflow in java/org/apache/tomcat/util/buf/Ascii.java in Apache Tomcat before 6.0.40, 7.x before 7.0.53, and 8.x before 8.0.4, when operated behind a reverse proxy, allows remote attackers to conduct HTTP request smuggling attacks via a crafted Content-Length HTTP header.

Affected versions

Maven

Package	Vulnerable	Fixed in
org.apache.tomcat:tomcat	`< 6.0.40`	`6.0.40`
org.apache.tomcat:tomcat	`>= 7.0.0, < 7.0.54`	`7.0.54`
org.apache.tomcat:tomcat	`>= 8.0.0, < 8.0.6`	`8.0.6`
org.apache.tomcat:tomcat-util	`< 6.0.40`	`6.0.40`
org.apache.tomcat:tomcat-util	`>= 7.0.0, < 7.0.54`	`7.0.54`
org.apache.tomcat:tomcat-util	`>= 8.0.0, < 8.0.6`	`8.0.6`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

org.apache.tomcat:tomcat Maven → `6.0.40`

maven

<dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat</artifactId><version>6.0.40</version></dependency>

gradle

implementation("org.apache.tomcat:tomcat:6.0.40")

org.apache.tomcat:tomcat-util Maven → `6.0.40`

maven

<dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat-util</artifactId><version>6.0.40</version></dependency>

gradle

implementation("org.apache.tomcat:tomcat-util:6.0.40")

Weakness

CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.

How to prevent it

Implementation: Construct HTTP headers very carefully, avoiding the use of non-validated input data.
Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. If an input does not strictly conform to specifications, reject it or transform it into something that conforms. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Implementation: Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2014-0099

Packages

github.com/apache/tomcat

Timeline

May 14, 2022 Published
Apr 14, 2025 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-69r9-qgr7-g2wj Apache Tomcat Missing Encryption of Sensitive Data vulnerability	High Known exploited	Also affects org.apache.tomcat:tomcat
GHSA-h3x4-894j-xpx5 Apache Tomcat's FORM authentication process has an Incorrect Authorization vulnerability	Critical	Also affects org.apache.tomcat:tomcat
GHSA-9xv2-5v5q-p794 Apache Tomcat's DIGEST authenticator has an Authentication Bypass by Capture-replay vulnerability	Critical	Also affects org.apache.tomcat:tomcat
GHSA-gcx9-497g-6cp6 Apache Tomcat has an Improper Access Control, Incorrect Authorization vulnerability	Critical	Also affects org.apache.tomcat:tomcat
GHSA-5m62-pw8w-7w9f Apache Tomcat - Security constraints not correctly applied	Critical	Also affects org.apache.tomcat:tomcat
GHSA-9m89-8frq-c98c Apache Tomcat - AJP secret compared in non-constant time	Low	Also affects org.apache.tomcat:tomcat
GHSA-5mp6-jrq3-r938 Apache Tomcat: LockOutRealm treats user names as case-sensitive	High	Also affects org.apache.tomcat:tomcat
GHSA-h6fc-48rj-7qqh Apache Tomcat - Digest authenticator will authenticate any unknown user	Critical	Also affects org.apache.tomcat:tomcat

Is this in your code?

MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.

Check your repos with MergeHarbor