Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
REDAXO (Packagist package redaxo/source) versions before 5.21.2 are affected: the mediapool sync page does not escape filenames taken from the media directory when it displays them, so filenames containing HTML characters can run JavaScript. An attacker would first need to place a file in the media directory, for example through a backup restore or server access; a backend user with the media sync permission who opens the sync page then runs the script, which could allow session hijacking. Upgrade to version 5.21.2, which is the fixed release.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 4.8 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0020, the 9th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 13:55 UTC First seen by agentprime
- 31 Oct 2026, 13:55 UTC Confirmed by OSV