Vulnerability · Published Aug 19, 2026 · Assigned by VulnCheck

CVE-2026-75583keeper.sh Calendar version prior to 2.18.14 SSRF Guard Bypass via DNS Rebinding

Low 3.5

In plain English

A low-severity server-side request forgery in keeper.sh from ridafkih. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities).

Severity (CVSS 3.1)3.5Low

Exploit odds (30 days)0.3%top 74.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
ridafkih	keeper.sh	0 – before 2.18.14

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N

References

Product Repository product
GitHub Security Advisory (GHSA-mxxg-qffg-j3p6) vendor-advisory
Patch Commit patch
https://www.vulncheck.com/advisories/keeper-sh-calendar-version-prior-to-ssrf-guard-bypass-via-dns-rebinding third-party-advisory