CVE-2015-3440

CVE Descriptions

Cross-site scripting (XSS) vulnerability in wp-includes/wp-db.php in WordPress before 4.2.1 allows remote attackers to inject arbitrary web script or HTML via a long comment that is improperly stored because of limitations on the MySQL TEXT data type.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V2	4.3		AV:N/AC:M/Au:N/C:N/I:P/A:N	nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

Date	EPSS V0	EPSS V1	EPSS V2 (> 2022-02-04)	EPSS V3 (> 2025-03-07)	EPSS V4 (> 2025-03-17)
2022-02-06	–	–	19.06%	–	–
2022-04-03	–	–	19.06%	–	–
2022-12-25	–	–	17.43%	–	–
2023-03-12	–	–	–	95.29%	–
2023-03-26	–	–	–	95.03%	–
2023-05-28	–	–	–	94.96%	–
2023-07-30	–	–	–	94.66%	–
2024-04-14	–	–	–	94.4%	–
2024-06-02	–	–	–	94.4%	–
2024-07-14	–	–	–	93.4%	–
2024-09-01	–	–	–	92.96%	–
2024-12-08	–	–	–	91.73%	–
2024-12-22	–	–	–	64.1%	–
2025-01-19	–	–	–	64.1%	–
2025-03-18	–	–	–	–	17.18%
2025-03-30	–	–	–	–	17.18%
2025-04-06	–	–	–	–	10.33%
2025-04-15	–	–	–	–	10.33%
2025-04-15	–	–	–	–	10.33,%

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Date	Percentile
2022-02-06	94%
2022-04-03	96%
2022-12-25	96%
2023-03-12	99%
2023-03-26	99%
2023-05-28	99%
2023-07-30	99%
2024-04-14	99%
2024-06-02	99%
2024-07-14	99%
2024-09-01	99%
2024-12-08	99%
2024-12-22	98%
2025-01-19	98%
2025-03-18	95%
2025-03-30	94%
2025-04-06	92%
2025-04-15	93%
2025-04-15	93%

Exploit information

Exploit Database EDB-ID : 36844

Publication date : 2015-04-26 22h00 +00:00
Author : klikki
EDB Verified : Yes

Source: http://klikki.fi/adv/wordpress2.html ## Overview Current versions of WordPress are vulnerable to a stored XSS. An unauthenticated attacker can inject JavaScript in WordPress comments. The script is triggered when the comment is viewed. If triggered by a logged-in administrator, under default settings the attacker can leverage the vulnerability to execute arbitrary code on the server via the plugin and theme editors. Alternatively the attacker could change the administrator’s password, create new administrator accounts, or do whatever else the currently logged-in administrator can do on the target system. ## Details If the comment text is long enough, it will be truncated when inserted in the database. The MySQL TEXT type size limit is 64 kilobytes, so the comment has to be quite long. The truncation results in malformed HTML generated on the page. The attacker can supply any attributes in the allowed HTML tags, in the same way as with the two recently published stored XSS vulnerabilities affecting the WordPress core. The vulnerability bears a similarity to the one reported by Cedric Van Bockhaven in 2014 (patched this week, after 14 months). Instead of using an invalid character to truncate the comment, this time an excessively long comment is used for the same effect. In these two cases, the injected JavaScript apparently can't be triggered in the administrative Dashboard so these exploits seem to require getting around comment moderation e.g. by posting one harmless comment first. The similar vulnerability released by Klikki in November 2014 could be exploited in the administrative Dashboard while the comment is still in the moderation queue. Some exploit attempts of this have been recently reported in the wild. ## Proof of Concept Enter as a comment text: <a title='x onmouseover=alert(unescape(/hello%20world/.source)) style=position:absolute;left:0;top:0;width:5000px;height:5000px AAAAAAAAAAAA...[64 kb]..AAA'></a> Confirmed vulnerable: WordPress 4.2, 4.1.2, 4.1.1, 3.9.3. Tested with MySQL versions 5.1.53 and 5.5.41. ## Demo https://www.youtube.com/watch?v=OCqQZJZ1Ie4