SB2026041618 - Multiple vulnerabilities in Synology DSM

Description

This security bulletin contains information about 11 vulnerabilities.

1) CRLF injection (CVE-ID: CVE-2026-40530)

CWE-ID: CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to read or write arbitrary files and cause a denial of service.

The vulnerability exists due to improper neutralization of CRLF sequences in DSM when handling crafted input. A remote user can send specially crafted input to read or write arbitrary files and cause a denial of service.

User interaction is required.

2) SQL injection (CVE-ID: CVE-2026-4036)

CWE-ID: CWE-89 - Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to disclose sensitive information.

The vulnerability exists due to SQL injection in DSM when processing crafted SQL-related input. A remote user can send a specially crafted request to disclose sensitive information.

3) Integer overflow (CVE-ID: CVE-2026-40531)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to integer overflow in DSM when processing crafted input. A remote user can send a specially crafted request to cause a denial of service.

4) Forced browsing (CVE-ID: CVE-2026-40532)

CWE-ID: CWE-425 - Direct Request ('Forced Browsing')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote user to disclose sensitive information.

The vulnerability exists due to direct request forced browsing in DSM when handling requests to restricted resources. A remote user can send a specially crafted request to disclose sensitive information.

5) Stored cross-site scripting (CVE-ID: CVE-2026-40534)

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

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear

The vulnerability allows a remote user to execute arbitrary script in a user's browser.

The vulnerability exists due to cross-site scripting in DSM when rendering crafted web content. A remote user can inject specially crafted content to execute arbitrary script in a user's browser.

User interaction is required.

6) Path traversal (CVE-ID: CVE-2026-40536)

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to disclose limited information.

The vulnerability exists due to path traversal in DSM when processing crafted path input. A remote user can send a specially crafted request to disclose limited information.

7) Server-Side Request Forgery (SSRF) (CVE-ID: CVE-2026-40537)

CWE-ID: CWE-918 - Server-Side Request Forgery (SSRF)

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to disclose limited information.

The vulnerability exists due to server-side request forgery in DSM when processing crafted server-side requests. A remote user can send a specially crafted request to disclose limited information.

8) Exposure of Sensitive Information Through Data Queries (CVE-ID: CVE-2026-40533)

CWE-ID: CWE-202 - Exposure of Sensitive Information Through Data Queries

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to obtain non-sensitive information.

The vulnerability exists due to exposure of sensitive information through data queries in DSM when processing data queries. A remote attacker can send a specially crafted request to obtain non-sensitive information.

9) Path traversal (CVE-ID: CVE-2026-40535)

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to read or write limited files and cause a denial of service.

The vulnerability exists due to path traversal in DSM when processing crafted path input. A remote attacker can send a specially crafted request to read or write limited files and cause a denial of service.

10) Improper Restriction of Excessive Authentication Attempts (CVE-ID: CVE-2026-40538)

CWE-ID: CWE-307 - Improper Restriction of Excessive Authentication Attempts

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to obtain non-sensitive information.

The vulnerability exists due to improper restriction of excessive authentication attempts in DSM when handling authentication attempts. A remote attacker can perform repeated authentication attempts to obtain non-sensitive information.

11) Improper Certificate Validation (CVE-ID: CVE-2026-40539)

CWE-ID: CWE-295 - Improper Certificate Validation

CVSSv4: CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to read or write arbitrary files and cause a denial of service.

The vulnerability exists due to improper certificate validation in DSM when establishing adjacent-network connections. A remote attacker can perform a man-in-the-middle attack to read or write arbitrary files and cause a denial of service.

User interaction is required.

Remediation

Install update from vendor's website.

References

• https://www.synology.com/en-global/security/advisory/Synology_SA_26_06 
• https://www.synology.com/en-global/security/advisory/Synology_SA_26_06