CVE-2026-89321
OpenVSX WebResourceService Unbounded Decompression Disk Exhaustion
Description
Publishing limits the compressed size of a VSIX (ovsx.publishing.max-content-size, 512 MB by default) but nothing limited how large an entry becomes when opened. On the first request to /vscode/unpkg/{namespace}/{extension}/{version}/{path}, WebResourceService opened the entry with ZipFile.getInputStream() and passed the decompressed stream to Files.copy(), which ran to the end of the stream without counting bytes written. The result was cached under java.io.tmpdir, and that cache evicted by entry count (150), not by size, so it placed no bound on disk usage. A publisher with access only to their own namespace could therefore upload a small, highly compressible VSIX and cause the server to write far larger files to the temp filesystem — repeating with different files or versions, since a repeat request is served from the cache. Impact observed: the temp filesystem filled; requests for files not already cached returned 500 with No space left on device; a failed extraction left a partial cache file that blocked later attempts at that path; publishing failed with Failed to read extension file. Metadata and already-cached files kept working, and the server did not stop. Triggering the extraction needs no authentication — only the upload does.
INFO
Published Date :
Sept. 14, 2026, 9:17 a.m.
Last Modified :
Sept. 14, 2026, 9:17 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-89321
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | e51fbebd-6053-4e49-959f-1b94eeb69a2c | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Implement decompression size limits.
- Limit disk space usage for cached files.
- Update relevant file handling components.
- Monitor filesystem usage.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-89321.
| URL | Resource |
|---|---|
| https://github.com/eclipse-openvsx/openvsx/pull/2060 | |
| https://github.com/eclipse-openvsx/openvsx/security/advisories/GHSA-h685-gqw7-fqw7 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-89321 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-89321
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-89321 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-89321 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 14, 2026
Action Type Old Value New Value Added Description Publishing limits the compressed size of a VSIX (ovsx.publishing.max-content-size, 512 MB by default) but nothing limited how large an entry becomes when opened. On the first request to /vscode/unpkg/{namespace}/{extension}/{version}/{path}, WebResourceService opened the entry with ZipFile.getInputStream() and passed the decompressed stream to Files.copy(), which ran to the end of the stream without counting bytes written. The result was cached under java.io.tmpdir, and that cache evicted by entry count (150), not by size, so it placed no bound on disk usage. A publisher with access only to their own namespace could therefore upload a small, highly compressible VSIX and cause the server to write far larger files to the temp filesystem — repeating with different files or versions, since a repeat request is served from the cache. Impact observed: the temp filesystem filled; requests for files not already cached returned 500 with No space left on device; a failed extraction left a partial cache file that blocked later attempts at that path; publishing failed with Failed to read extension file. Metadata and already-cached files kept working, and the server did not stop. Triggering the extraction needs no authentication — only the upload does. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L Added CWE CWE-409 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89321.json">CVE-2026-89321</a> Added Reference https://github.com/eclipse-openvsx/openvsx/pull/2060 Added Reference https://github.com/eclipse-openvsx/openvsx/security/advisories/GHSA-h685-gqw7-fqw7