# CVE-2026-123523: Vikunja before 2.7.1 Memory Exhaustion via Unbounded Avatar Size Cache

Status: published. Published: 2026-11-08. Updated: 2026-11-12.

Vikunja before 2.7.1 contains an uncontrolled resource consumption vulnerability that allows authenticated users to exhaust server memory by requesting avatars at many distinct sizes. Attackers can upload a noisy avatar and fetch it at each size up to 1024, caching roughly a gigabyte per account without eviction and causing the API process to be OOM-killed.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- go-vikunja / vikunja (code.vikunja.io/api): ≥ 0; < 2.7.1 (affected, semver); 2.7.1 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.1 (high); 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; source: CNA: VulnCheck

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CVSS 4.0: 7.1 (high); 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.31% as of 2026-11-12; percentile 23.78%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-770

## Exploit evidence

- exploit: https://github.com/go-vikunja/vikunja/security/advisories/GHSA-3x3m-2j93-w46j (ADP: CISA-ADP)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-3x3m-2j93-w46j (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/vikunja-before-2.7.1-memory-exhaustion-via-unbounded-avatar-size-cache (CNA: VulnCheck; third-party-advisory)

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-3x3m-2j93-w46j (ADP: CISA-ADP; exploit)

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-3x3m-2j93-w46j (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/vikunja-before-2.7.1-memory-exhaustion-via-unbounded-avatar-size-cache (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123523; retrieved 2026-11-12; source updated 2026-11-12

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123523; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-123523; retrieved 2026-11-12; source updated Not reported

Revision: 688126a00bcc12c96a47b0a0534c6ac35dcb7c8d6b58d0d4fd720a83271dc480

Canonical: https://y2.dev/cve/CVE-2026-123523

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.