VulnerabilityPublished 4 Dec 2025

CVE-2025-29843: Synology Router Manager (SRM) · Path Traversal

Affects Synology Router Manager (SRM)Source CVE Database V5

Not known to be exploited · CVSS 5.4 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

5.4Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Synology Synology Router Manager (SRM)	Affected =1.3	Fixed in–

AI-suggested

Apply official patches from Synology as soon as they are released to address CVE-2025-29843.
Restrict access to the FileStation interface and the SRM management console to trusted networks and users only, using network segmentation and firewall rules.
Enforce strong authentication policies, including multi-factor authentication (MFA), to reduce the risk of credential compromise.
Monitor logs for unusual file access or modification activities, particularly related to image files handled by FileStation.
Disable or limit the use of the thumb CGI component if not required, to reduce the attack surface.
Educate users on phishing and credential security to prevent unauthorized access.
Regularly audit SRM devices for firmware versions and configuration compliance.
Consider deploying intrusion detection systems (IDS) to detect exploitation attempts targeting this vulnerability.

Description

A vulnerability in FileStation thumb cgi allows remote authenticated users to read/write image files.

Impact

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and integrity of data managed via Synology SRM devices. Unauthorized read/write access to image files could lead to exposure of sensitive visual data or insertion of malicious files that may facilitate further compromise. Organizations using SRM in critical infrastructure or business environments may face risks of data leakage or tampering. Since the vulnerability requires authentication, the risk is higher in environments with weak credential management or where attackers can obtain valid user credentials through phishing or other means. The lack of availability impact reduces the risk of service disruption but does not eliminate the threat of stealthy data compromise. Given the widespread use of Synology devices in Europe, especially in small and medium enterprises, the vulnerability could be exploited for lateral movement or espionage if left unmitigated.

References

synology.com/en-global/security/advisory/Synology_SA_25_04 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Dec 2025, 15:31 UTC

Technical details

References

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