Plex Media Server External Control of File Name or Path
CVE-2026-96656 is a high-severity external control of file name or path vulnerability in Media Server from Plex, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. The record lists version 1.43.3.10861 as the first without the flaw, so updating Media Server to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on October 20, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Media Server to 1.43.3.10861 or a later version.
- CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Plex | Media Server | before 1.43.3.10861 | 1.43.3.10861 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- HighAdministrator-level access is required first.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.6 | High | CNA |
| CVSS 3.1 | 7.2 | High | CNA |
Official description
Plex Media Server before 1.43.3.10861 allows an admin user to write arbitrary files that may be executed on load. The preference TranscoderH264Options is appended verbatim to x264's option string on every transcode. At startup, all .so files are run without signature, execute bit, or symbol checks.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: External Control of File Name or Path
The product allows user input to control or influence paths or file names that are used in filesystem operations.
How developers prevent this class of flaw
- When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to inbox.txt and ID 2 could map to profile.txt. Features such as the ESAPI AccessReferenceMap provide this capability.
- Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More External Control of File Name or Path vulnerabilities (CWE-73)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Record last changed materially (score, affected products, status or references).
- Deadline for US federal agencies to remediate, set by CISA.
References
Patches and release notes
- forums.plex.tv/t/plex-media-server/30447/711Release Notes
Third-party and government advisories
- raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-266-01.jsonThird Party Advisory
- cve.org/CVERecord?id=CVE-2026-96656Third Party Advisory, VDB Entry
- zmain.info/blog/plex2shellThird Party Advisory
- boredhackerblog.info/2026/10/plex-vulnerabilities-being-exploited-in.htmlThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-96656US Government Resource
Our coverage
Other vulnerabilities in Media Server
- 4.3 Medium severity
- 6.5 Medium severity
- 4.3 Medium severity
- 7.1 High severity
- 8.5 High severity
- 7.2 High severity
Plex Media Server Remote Code Execution Exploited
Recent External Control of File Name or Path vulnerabilities
- 7.8 High severity
- 8.4 High severity
- 8.8 High severity
- 8.3 High severity
- 9.8 Critical severity
- 8.1 High severity
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