Jenkins Email Extension Plugin: Attackers able to control email content may specify file: URLs for images to read arbitrary files from Jenkins controller filesystem

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-48920: 0.29% estimated exploitation activity in the next 30 days; percentile 21.39 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Jenkins Email Extension Plugin 1933.v45cec755423f and earlier includes a feature that allows inlining images as base64 in email content by setting the data-inline attribute. No restrictions are placed on the image URLs that can be inlined. This allows attackers able to control the email content to specify file: URLs for images to read arbitrary files from the Jenkins controller filesystem. The feature allowing inlining images as base64 in email content by setting the data-inline attribute is removed from Email Extension Plugin 1933.1935.v276319e3cc47.

Published by the source

27 May 2026, 15:33 UTC

Last modified by the source

1 Jul 2026, 19:42 UTC

Source last checked

26 Oct 2026, 16:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mq58-m26g-46gp

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# Patch Next advisory brief: CVE-2026-48920

Advisory: Jenkins Email Extension Plugin: Attackers able to control email content may specify `file:` URLs for images to read arbitrary files from Jenkins controller filesystem
IDs: CVE-2026-48920, GHSA-mq58-m26g-46gp
Record: https://patchnext.com/advisories/cve-2026-48920 (revision 1, source checked 26 Oct 2026, 16:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.jenkins-ci.plugins:email-ext 1933.1935.v276319e3cc47. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.jenkins-ci.plugins:email-ext: affected < 1933.1935.v276319e3cc47; fixed in 1933.1935.v276319e3cc47

## Suggested inspection (read-only)
- Maven org.jenkins-ci.plugins:email-ext: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.jenkins-ci.plugins:email-ext.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mq58-m26g-46gp (GitHub-reviewed advisory GHSA-mq58-m26g-46gp lists affected ranges: Maven org.jenkins-ci.plugins:email-ext >=0 <1933.1935.v276319e3cc47)

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