# What is CVE-2006-3918?

> CVE-2006-3918 is a medium-severity flaw (CVSS 4.3) in HTTP Server from Apache, published on 28 July 2006. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 95%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2006-3918

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 57 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 4.3 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 95% (latest exploit-likelihood forecast)
- **Published:** 28 July 2006
- **Record last updated:** 16 June 2026
- **Main product:** HTTP Server from Apache
- **Affected products:** 5

## What is CVE-2006-3918? In plain terms

It can be attacked from anywhere on the internet without logging in. If it works, the attacker can change some data.

### The official description

http_protocol.c in (1) IBM HTTP Server 6.0 before 6.0.2.13 and 6.1 before 6.1.0.1, and (2) Apache HTTP Server 1.3 before 1.3.35, 2.0 before 2.0.58, and 2.2 before 2.2.2, does not sanitize the Expect header from an HTTP request when it is reflected back in an error message, which might allow cross-site scripting (XSS) style attacks using web client components that can send arbitrary headers in requests, as demonstrated using a Flash SWF file.

### What kind of flaw is it?

- CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Some conditions needed
- Login needed first: No login needed
- What an attacker gets: Can change some data

Severity vector: `AV:N/AC:M/Au:N/C:N/I:P/A:N`

## Is CVE-2006-3918 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 95%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 95%, 95%, 95%, 95%, 95%, 95%, 95%.

### Timeline

- 28 July 2006: Published
- 16 June 2026: Record last updated

### How Precursor Intelligence ranks it

CVE-2006-3918 scores **57 out of 100 (Medium)**, with the action "Plan remediation".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2006-3918?

The published record lists 5 products. Versions are as published: "1.3.3 to before 1.3.35" means from 1.3.3 up to, but not including, 1.3.35.

- [HTTP Server](https://www.precursorintelligence.com/product/apache/http_server) by [Apache](https://www.precursorintelligence.com/vendors/apache) (Application): 1.3.3 to before 1.3.35
- [Ubuntu Linux](https://www.precursorintelligence.com/product/canonical/ubuntu_linux) by [Canonical](https://www.precursorintelligence.com/vendors/canonical) (Operating system): 6.06, 6.10, 7.04, 7.10
- [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 3.1
- [Enterprise Linux Server](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 2.0
- [Enterprise Linux Workstation](https://www.precursorintelligence.com/product/redhat/enterprise_linux_workstation) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 2.0

## How do I fix CVE-2006-3918?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [secunia.com](http://secunia.com/advisories/21172) (Not applicable, Patch, Vendor advisory)
- [secunia.com](http://secunia.com/advisories/21174) (Not applicable, Patch, Vendor advisory)
- [svn.apache.org](http://svn.apache.org/viewvc?view=rev&revision=394965) (Exploit, Vendor advisory)
- [archives.neohapsis.com](http://archives.neohapsis.com/archives/bugtraq/2006-05/0151.html) (Broken link, Exploit)
- [archives.neohapsis.com](http://archives.neohapsis.com/archives/bugtraq/2006-07/0425.html) (Broken link, Exploit)
- [kb.vmware.com](http://kb.vmware.com/KanisaPlatform/Publishing/466/5915871_f.SAL_Public.html) (Third-party advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2008-04/msg00004.html) (Mailing list, Third-party advisory)
- [marc.info](http://marc.info/?l=bugtraq&m=125631037611762&w=2) (Issue tracking, Mailing list, Third-party advisory)
- [marc.info](http://marc.info/?l=bugtraq&m=129190899612998&w=2) (Issue tracking, Mailing list, Third-party advisory)
- [marc.info](http://marc.info/?l=bugtraq&m=130497311408250&w=2) (Issue tracking, Mailing list, Third-party advisory)
- [openbsd.org](http://openbsd.org/errata.html#httpd2) (Third-party advisory)
- [rhn.redhat.com](http://rhn.redhat.com/errata/RHSA-2006-0618.html) (Third-party advisory)
- [rhn.redhat.com](http://rhn.redhat.com/errata/RHSA-2006-0692.html) (Third-party advisory)
- [secunia.com](http://secunia.com/advisories/21399) (Not applicable)
- [secunia.com](http://secunia.com/advisories/21478) (Not applicable)
- [secunia.com](http://secunia.com/advisories/21598) (Not applicable)
- [secunia.com](http://secunia.com/advisories/21744) (Not applicable)
- [secunia.com](http://secunia.com/advisories/21848) (Not applicable)
- [secunia.com](http://secunia.com/advisories/21986) (Not applicable)
- [secunia.com](http://secunia.com/advisories/22140) (Not applicable)
- [secunia.com](http://secunia.com/advisories/22317) (Not applicable)
- [secunia.com](http://secunia.com/advisories/22523) (Not applicable)
- [secunia.com](http://secunia.com/advisories/28749) (Not applicable)
- [secunia.com](http://secunia.com/advisories/29640) (Not applicable)
- [secunia.com](http://secunia.com/advisories/40256) (Not applicable)
- [securityreason.com](http://securityreason.com/securityalert/1294) (Exploit, Third-party advisory)
- [securitytracker.com](http://securitytracker.com/id?1016569) (Broken link, Third-party advisory, Vulnerability database)
- [support.avaya.com](http://support.avaya.com/elmodocs2/security/ASA-2006-194.htm) (Third-party advisory)
- [www-1.ibm.com](http://www-1.ibm.com/support/docview.wss?uid=swg1PK24631) (Third-party advisory)
- [www-1.ibm.com](http://www-1.ibm.com/support/docview.wss?uid=swg24013080) (Third-party advisory)
- [debian.org](http://www.debian.org/security/2006/dsa-1167) (Third-party advisory)
- [f-secure.com](http://www.f-secure.com/en_EMEA/support/security-advisory/fsc-2010-2.html) (Third-party advisory)
- [novell.com](http://www.novell.com/linux/security/advisories/2006_51_apache.html) (Third-party advisory)
- [redhat.com](http://www.redhat.com/support/errata/RHSA-2006-0619.html) (Third-party advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/19661) (Third-party advisory, Vulnerability database)
- [securitytracker.com](http://www.securitytracker.com/id?1024144) (Broken link, Third-party advisory, Vulnerability database)
- [ubuntu.com](http://www.ubuntu.com/usn/usn-575-1) (Third-party advisory)
- [vupen.com](http://www.vupen.com/english/advisories/2006/2963) (Permissions required)
- [vupen.com](http://www.vupen.com/english/advisories/2006/2964) (Permissions required)
- [vupen.com](http://www.vupen.com/english/advisories/2006/3264) (Permissions required)
- [vupen.com](http://www.vupen.com/english/advisories/2006/4207) (Permissions required)
- [vupen.com](http://www.vupen.com/english/advisories/2006/5089) (Permissions required)
- [vupen.com](http://www.vupen.com/english/advisories/2010/1572) (Permissions required)
- [www14.software.ibm.com](http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd?mode=18&ID=3117) (Broken link)
- [lists.apache.org](https://lists.apache.org/thread.html/r5419c9ba0951ef73a655362403d12bb8d10fab38274deb3f005816f5%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r5f9c22f9c28adbd9f00556059edc7b03a5d5bb71d4bb80257c0d34e4%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r652fc951306cdeca5a276e2021a34878a76695a9f3cfb6490b4a6840%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E)
- [lists.apache.org](https://lists.apache.org/thread.html/rafd145ba6cd0a4ced113a5823cdaff45aeb36eb09855b216401c66d6%40%3Ccvs.httpd.apache.org%3E)

## Questions

### What is CVE-2006-3918?

CVE-2006-3918 is a medium-severity flaw in HTTP Server from Apache, published on 28 July 2006. It can be attacked from anywhere on the internet without logging in. If it works, the attacker can change some data.

### How serious is CVE-2006-3918?

It scores 4.3 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2006-3918 is 57 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2006-3918 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 95%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2006-3918 affect?

For HTTP Server from Apache: 1.3.3 to before 1.3.35. The record lists 5 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2006-3918?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2006-3918 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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