# What is CVE-2017-5223?

> CVE-2017-5223 is a medium-severity flaw (CVSS 5.5) in Phpmailer from Phpmailer Project, published on 16 January 2017. 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 2.1%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2017-5223

## At a glance

- **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle.
- **Precursor Intelligence risk score:** 39 out of 100 (Low); action: Monitor. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 5.5 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:** 2.1% (latest exploit-likelihood forecast)
- **Published:** 16 January 2017
- **Record last updated:** 20 April 2025
- **Main product:** Phpmailer from Phpmailer Project
- **Affected products:** 1

## What is CVE-2017-5223? In plain terms

An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data.

### The official description

An issue was discovered in PHPMailer before 5.2.22. PHPMailer's msgHTML method applies transformations to an HTML document to make it usable as an email message body. One of the transformations is to convert relative image URLs into attachments using a script-provided base directory. If no base directory is provided, it resolves to /, meaning that relative image URLs get treated as absolute local file paths and added as attachments. To form a remote vulnerability, the msgHTML method must be called, passed an unfiltered, user-supplied HTML document, and must not set a base directory.

### What kind of flaw is it?

- CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data

Severity vector: `CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`

## Is CVE-2017-5223 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 2.1%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 2.1%, 2.1%, 2.1%, 2.1%, 2.1%, 2.1%, 2.1%.

### Timeline

- 16 January 2017: Published
- 20 April 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2017-5223 scores **39 out of 100 (Low)**, with the action "Monitor".

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-2017-5223?

The published record lists 1 product.

- [Phpmailer](https://www.precursorintelligence.com/product/phpmailer_project/phpmailer) by [Phpmailer Project](https://www.precursorintelligence.com/vendors/phpmailer_project) (Application): up to 5.2.21

## How do I fix CVE-2017-5223?

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 advisory 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

- [github.com](https://github.com/PHPMailer/PHPMailer/blob/master/SECURITY.md) (Issue tracking, Patch, Third-party advisory)
- [kalilinux.co](http://kalilinux.co/2017/01/12/phpmailer-cve-2017-5223-local-information-disclosure-vulnerability-analysis/) (Exploit, Third-party advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/95328) (Third-party advisory, Vulnerability database)
- [exploit-db.com](https://www.exploit-db.com/exploits/43056/)

## Questions

### What is CVE-2017-5223?

CVE-2017-5223 is a medium-severity flaw in Phpmailer from Phpmailer Project, published on 16 January 2017. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data.

### How serious is CVE-2017-5223?

It scores 5.5 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2017-5223 is 39 out of 100, which is Low. Its action is "Monitor". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

### Is CVE-2017-5223 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 2.1%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2017-5223 affect?

For Phpmailer from Phpmailer Project: up to 5.2.21.

### How do I fix CVE-2017-5223?

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-2017-5223 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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