CVE-2026-75583 keeper.sh Calendar version prior to 2.18.14 SSRF Guard Bypass via DNS Rebinding
Authenticated attackers can bypass SSRF guards via DNS rebinding to access private network resources and cloud metadata endpoints.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-75583?
CVE-2026-75583 is a low-severity server-side request forgery vulnerability in ridafkih keeper.sh, published on 19 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-75583?
How do I fix CVE-2026-75583?
No fix has been published for CVE-2026-75583 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-75583 being exploited?
There is no known exploitation of CVE-2026-75583 in the wild and no public exploit code.
Sources
Also known as GHSA-mxxg-qffg-j3p6.