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CVE-2026-75583· NVD / CVE Program· CNA VulnCheck

keeper.sh Calendar version prior to 2.18.14 SSRF Guard Bypass via DNS Rebinding

keeper.sh's calendar module version prior to 2.18.14 contains a server-side request forgery (SSRF) guard bypass vulnerability that allows authenticated attackers to reach private network addresses by exploiting a DNS rebinding attack against the two-phase URL validation and connection flow. The SSRF guard validates a hostname's resolved IP addresses but discards them before the actual HTTP connection is opened, allowing an attacker who controls authoritative DNS to return a public address during validation and a private address during the subsequent independent socket-level DNS resolution, causing the guard to pass while the outbound connection reaches internal infrastructure such as cloud instance metadata endpoints.

LowCVSS 2.3 · v4.0—No exploit Fix available

Noroxi analysis

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Published
Aug 19, 2026
Updated
Sep 24, 2026
EPSS
0.3% · 23th percentile
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Report tools

JSON

Action score

9

Monitor

Low priority for now.

CVSS
9 / 40 · 2.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
2.3
NVD has not scored this yet; the score shown is the CNA’s.

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

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

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • ridafkih keeper.sh

    • before 2.18.14affected · semver

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
ridafkih keeper.sh2.18.14Vendor (CNA)

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.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

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.

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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.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
X

Weakness class (CWE)

CWE-918 · Server-Side Request Forgery (SSRF)

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records