CVE-2026-34975 Other in plunk
Authenticated users can inject arbitrary email headers via CRLF characters in Plunk, enabling sender spoofing and silent forwarding.
- 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-2026-34975?
CVE-2026-34975 is a high-severity vulnerability in useplunk plunk, published on 6 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Plunk is an open-source email platform built on top of AWS SES. Prior to 0.8.0, a CRLF header injection vulnerability was discovered in SESService.ts, where user-supplied values for from.name, subject, custom header keys/values, and attachment filenames were interpolated directly into raw MIME messages without sanitization. An authenticated API user could inject arbitrary email headers (e.g. Bcc, Reply-To) by embedding carriage return/line feed characters in these fields, enabling silent email forwarding, reply redirection, or sender spoofing. The fix adds input validation at the schema level to reject any of these fields containing \r or \n characters, consistent with the existing validation already applied to the contentId field. This vulnerability is fixed in 0.8.0.
Weakness: CWE-93
Which versions are affected by CVE-2026-34975?
It affects 1 product.
Products include Useplunk Plunk.
How do I fix CVE-2026-34975?
No fix has been published for CVE-2026-34975 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-34975 being exploited?
There is no known exploitation of CVE-2026-34975 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in useplunk plunk
Sources
Also known as GHSA-2mvm-rg5v-7hfq.