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CVE-2018-8927· NVD / CVE Program· CNA synology

Improper authorization vulnerability in SYNO.Cal.Event in Calendar before 2.1.2-0511 allows remote authenticated users to create arbitrary e

Improper authorization vulnerability in SYNO.Cal.Event in Calendar before 2.1.2-0511 allows remote authenticated users to create arbitrary events via the (1) cal_id or (2) original_cal_id parameter.

MediumCVSS 6.5 · v3.0—No exploit No fix recorded
Published
Jun 14, 2018
Updated
Jun 16, 2026
EPSS
0.9% · 58th percentile
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Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

CNA vs NVD score

NVD
6.5
CNA · synology
5.4
1.1 point gap

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
synologycalendar

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • synology calendarbefore 2.1.2-0511

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 Calendar

    • unspecified and later · before 2.1.2-0511affected

Same product

synology: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-11829OS command injection vulnerability in drivers_syno_import_user.php in Synology Calendar before 2.3.1-0617 allows remote attackers to execute
    40Plan
  • CVE-2022-22686Cross-Site Request Forgery (CSRF) vulnerability in webapi component in Synology Calendar before 2.3.4-0631 allows remote authenticated users
    32Monitor
  • CVE-2021-34812Use of hard-coded credentials vulnerability in php component in Synology Calendar before 2.4.0-0761 allows remote attackers to obtain sensit
    30Monitor
  • CVE-2018-13299Relative path traversal vulnerability in Attachment Uploader in Synology Calendar before 2.2.2-0532 allows remote authenticated users to upl
    26Monitor
  • CVE-2017-15891Improper access control vulnerability in SYNO.Cal.EventBase in Synology Calendar before 2.0.1-0242 allows remote authenticated users to modi
    26Monitor
  • CVE-2019-11820Information exposure through process environment vulnerability in Synology Calendar before 2.3.3-0620 allows local users to obtain credentia
    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.

EPSS, last 120 days

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 researchers

Finders, 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.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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.

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Change 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.

All records