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VulnerabilityPublished

CVE-2026-34975: useplunk plunk · CRLF Injection

Affects useplunk plunkSource CVE Database V5

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Not known to be exploited · CVSS 8.5 High : upgrade to 0.8.0 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
8.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.8.0
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade plunk and useplunk/plunk to 0.8.0.

Affected software

ProductAffectedFixed in
useplunkplunkAffected
  • <0.8.0
Fixed in
  • 0.8.0
GitHubuseplunk/plunkpkg:github/useplunk/plunkOther threatsAffected
  • <0.8.0
Fixed in
  • 0.8.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in plunk version 0.8.0, which adds input validation to reject carriage return and line feed characters in user-supplied email header fields and attachment filenames. Since plunk is a cloud-hosted service, the vendor manages remediation server-side. Users should ensure they are using version 0.8.0 or later. Check the vendor advisory for confirmation of patch deployment status. No additional mitigation is required if the service is updated.

Description

CVE-2026-34975 is a high-severity CRLF injection vulnerability in the open-source email platform plunk (useplunk) versions prior to 0.8.0. The flaw allows authenticated API users to inject arbitrary email headers by embedding carriage return and line feed characters in certain user-supplied fields such as from.name, subject, custom header keys/values, and attachment filenames. This can lead to silent email forwarding, reply redirection, or sender spoofing. The vulnerability is fixed in version 0.8.0 by adding input validation to reject these characters in the affected fields. The platform is cloud-hosted, and the vendor manages remediation for the service.

References

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