Lack of administrator control over security vulnerability in client.cgi in Synology SSL VPN Client before 1.2.5-0226 allows remote attackers
Lack of administrator control over security vulnerability in client.cgi in Synology SSL VPN Client before 1.2.5-0226 allows remote attackers to conduct man-in-the-middle attacks via the (1) command, (2) hostname, or (3) port parameter.
- Published
- Apr 1, 2019
- Updated
- Jun 16, 2026
- EPSS
- 1.4% · 71th percentile
- CWE
- CWE-671
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Report tools
Action score
29
Monitor
Low priority for now.
- CVSS
- 29 / 40 · 7.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.4%
CNA vs NVD score
- NVD
- 7.4
- CNA · synology
- 8.8
- 1.4 point gap
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| synology | ssl vpn client | cpe:2.3:a:synology:ssl_vpn_client |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- synology ssl vpn clientbefore 1.2.5-0226
Versions reported by the vendor
Affected version ranges reported by the assigning authority (synology). Independent of NVD's CPE analysis and usually ahead of it.
Synology SSL VPN Client
- unspecified and later · before 1.2.5-0226affected
Same product
synology: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-47961A plaintext storage of a password vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access or influence 32Monitor
- CVE-2018-8929Improper restriction of communication channel to intended endpoints vulnerability in HTTP daemon in Synology SSL VPN Client before 1.2.4-02232Monitor
- CVE-2021-47960A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to 26Monitor
- CVE-2023-5748Buffer copy without checking size of input ('Classic Buffer Overflow') vulnerability in cgi component in Synology SSL VPN Client before 1.4.22Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-671 · Lack of Administrator Control over SecurityCVSS vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.