Published:2021/04/22  Last Updated:2021/04/22

yappa-ng vulnerable to cross-site scripting


yappa-ng contains a cross-site scripting vulnerability.

Vendor Information

Developer: yet another PHP photo album next generation (according to the original report submitted by the reporter)

Product name and version: yappa-ng 2.3.2


yappa-ng <> provided by yet another PHP photo album next generation (according to the original report submitted by the reporter) is a PHP photo gallery.
yappa-ng contains a cross-site scripting vulnerability (CWE-79) which allows unintentional script execution on the user's web browser.


An arbitrary script may be executed on the web browser of the user who is accessing a website that uses yappa-ng.


Consider stop using yappa-ng 2.3.2
Since the developer was unreachable, existence of any mitigations is unknown.

Vendor Opinion

None provided

JPCERT/CC Addendum

During the meeting of Committee for authorizing the disclosure of unresolved vulnerabilities held on January 22, 2021, it was judged that an advisory for this vulnerability shall be disclosed since all the criteria and conditions described below which are stated in Standards for Handling Vulnerability related Information of Software Products and Other and Information Security Early Warning Partnership Guideline have been satisfied.

  1. The developer of the product is unreachable:
    JPCERT/CC had tried to reach the developer for a period of time (more than 6 months) however there were no responses from the developer. Therefore the committee reached the conclusion that it is reasonable and appropriate to judge the developer is unreachable.

    - No response to 6 separate emails (sent from October 5, 2006 to September 12, 2011)
    - No response to disclosure of the developer's name (listed on September 29, 2011) in "List of unreachable developers" and to the disclosure of the name and its version (listed on December 16, 2011) in “Information Resuest” on JVN
    - No response to the announcement of screening procedure for vulnerability disclosure (sent on December 21, 2020)

  2. Existence of vulnerability has been verified:
    It was verified that the product contains a cross-site scripting vulnerability by IPA. Arbitrary script execution on the user's web browser was confirmed which violates the "Integrity" of the product. For verification details, refer to the “Verification” section.

  3. Not disclosing this case may result in the risk that product users will have no means to know of the existence of the vulnerability in the product:
    By checking the developer’s website, it is assumed that users are permitted to copy, revise, or distribute the product, and it is downloadable via internet. Therefore, the developer cannot directly contact all users of this product to notify of the cross-site scripting vulnerability.  It was determined that disclosure of this vulnerability is legitimate under these conditions.

  4. There are no particular reasons that would make disclosure inappropriate:
    After considering the developer’s stance and the risk to product users, the committee has judged that there are no particular reasons that would make disclosure inappropriate or that disclosure may cause any other issues.

Vulnerability Analysis by JPCERT/CC

Base Score: 6.1
Attack Vector(AV) Physical (P) Local (L) Adjacent (A) Network (N)
Attack Complexity(AC) High (H) Low (L)
Privileges Required(PR) High (H) Low (L) None (N)
User Interaction(UI) Required (R) None (N)
Scope(S) Unchanged (U) Changed (C)
Confidentiality Impact(C) None (N) Low (L) High (H)
Integrity Impact(I) None (N) Low (L) High (H)
Availability Impact(A) None (N) Low (L) High (H)
Base Score: 4.3
Access Vector(AV) Local (L) Adjacent Network (A) Network (N)
Access Complexity(AC) High (H) Medium (M) Low (L)
Authentication(Au) Multiple (M) Single (S) None (N)
Confidentiality Impact(C) None (N) Partial (P) Complete (C)
Integrity Impact(I) None (N) Partial (P) Complete (C)
Availability Impact(A) None (N) Partial (P) Complete (C)


Validation Information
The vulnerability was reported to IPA and its existence was confirmed by IPA.

Date of validation
・June 25, 2020

Validation environment (Server, Product version 2.3.2)
・CentOS Linux 7.8.2003
・Apache 2.4.6
・PHP 5.4.16
・yappa-ng 2.3.2

Validation environment (Client)
・Microsoft Windows 10 Pro (64-bit) 1909/18363.836
・Microsoft Internet Explorer11 11.836.18362.0 (XSS filter is disabled)
・Google Chrome 83.0.4103.97

Validation result
・The reproducibility confirmed on the web browsers opening yappa-ng page, specified below
 (yappa-ng 2.3.2)
 Microsoft Internet Explorer11 11.836.18362.0
 Google Chrome 83.0.4103.97


Other Information

JPCERT Reports
CERT Advisory
CPNI Advisory
CVE CVE-2008-6495
JVN iPedia JVNDB-2021-000909

Update History

Added JVN iPedia link under [Other Information] section.