vulnerability / NVI-00011683 / Revision 2
Vikunja: Denial of service via decompression bomb in the data import
GitHub lists this reviewed advisory for code.vikunja.io/api. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
6.5 MEDIUM (3.1)
disclosure@vulncheck.com severity; no combined Null risk score.
7.1 HIGH (4.0)
disclosure@vulncheck.com severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
code.vikunja.io/api
source listed<= 2.5.0
### Summary Vikunja lets you export your data as a zip and import it back. The import doesn't limit how large the archive expands to, how many files it contains, or how much storage one user can consume, and it appears to hold the whole archive in memory while processing it. Because the archive is compressed, a ~20 MB upload made of highly compressible content expands to tens of gigabytes once imported. A single crafted upload is enough to exhaust the server's memory or fill its disk and knock the whole instance offline. It can be repeated or run in parallel, since nothing stops a user from starting several imports at once. ### Details The import accepts an archive in the same layout the built-in export produces: a manifest describing projects and tasks, plus the attachment files those tasks reference. Each individual file inside the archive is size-checked, but there's no ceiling on the total uncompressed size or on the number of files, and there's no per-user storage quota anywhere. On top of that, the server seems to buffer every attachment in memory before writing it out, so the peak memory cost is the sum of all decompressed files at once, not one at a time. Compression is t
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-w7jp-mf2v-8342 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-91979 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.