CVE-2026-40853Discovered Published
Apache XML Graphics Batik: XSS via unencoded SVGFont metadata
View patch bundle on GitHubFull published report
The reviewed summary below describes the scope of the fixture testing.
Apache XML Graphics Batik: XSS via unencoded SVGFont metadata (CVE-2026-40853)
cve.now entry. Product: Apache XML Graphics
Batik (org.apache.xmlgraphics) (lab: gabriel-batikfont-app).
Eden terminates the HTTP connection to the affected product, evaluates a declarative policy and — in tier 2 — a separately compiled native Rust module under signed module authority, before any byte reaches the application. It does not patch the affected component; the vendor's fixed release remains the durable repair.
Status: Remediated (tier 1 + tier 2), live-proven 2026-11-11T17:04:17Z on the
installed eden-product-release:1.103.0 lab container.
The vulnerability
Batik persists SVG font metadata without encoding, so a crafted font element
stores script content that later renders as markup. The fixture
(make_batikfont, port 18328) reproduces the delivery shape: a font upload
carrying script/event-handler markers in font metadata records a stored-XSS
mark.
The Eden patch
Tier 1 — declarative policy (blunt, fail-closed): deny every request under
/batik/font, ordinary font uploads included — false positives measured
below.
Tier 2 — native Rust module gabriel_batikfont_v1 (surgical): refuses
font uploads carrying script/event-handler markers (<script, onload=);
ordinary font uploads pass unchanged.
Measured comparison (fixtures10, run 2026-11-11)
| Probe | Baseline | Tier 1 | Tier 2 (module) | Backend effect |
|---|---|---|---|---|
| benign font upload | 200 | 403 (false positive) | 200 | none |
| attack: script in font metadata | 200 (xss_font recorded) | 403 | 403 | blocked at tier 2 |
Performance trace (Eden telemetry, live 2026-11-11)
Measured with Eden's built-in request telemetry (gateway.request.baseline
spans, read back through /api/v1/analytics/telemetry?signal=traces), not
client wall-clock. Latency Eden introduces per remediation arm for this case:
| Arm | n | mean | p50 | p95 | min–max |
|---|---|---|---|---|---|
| Tier 1 — declarative policy, blocked request (403) | 15 | 27 µs | 22 µs | 51 µs | 14 µs–51 µs |
| Tier 2 — native module, benign passes through (200) | 22 | 383 µs | 357 µs | 518 µs | 321 µs–622 µs |
| Tier 2 — native module, attack refused (403) | 14 | 138 µs | 140 µs | 195 µs | 109 µs–195 µs |
Eden-added latency for the tier-2 remediation: benign requests complete in 383 µs mean (p50 357 µs, p95 518 µs) in-product, module evaluation included. Honest scope: lab fixtures on one host, fresh connection per measured request, warm requests only; module reactivated shards 2/2 with a fresh signed statement per measurement; spans carry the full authority lineage (module SHA-256, operation, publication). Not the EDEN-3640 performance qualification contract.
Tested against: eden-product-release:1.103.0-single (image sha256:809293e1f0b525ac…, build target
eden_service_single, tooling revision 81a0724a…). Raw data:
module2/telemetry-ab/batikfont-telemetry.json and module2/tier1-ab/batikfont-tier1.json.
Authority lifecycle and negatives
Import 201, activation: explicit_required; publisher enroll_key, host
inventory + approve, reader inspect refused 403; tampered-statement admit
400; invalid-signature admit 403; admit prepared (not serving), activate
→ receipt serving_now, applied shards 2/2. Revoke → the identical attack
gets 503 (fail-closed); re-approve + re-activate → 403 again. All recorded
in the evidence JSON.
Honest scope
The fixture reproduces the unencoded-metadata shape, not the full Batik font
pipeline. Bypass variants (case tricks, alternate event handlers, entity
encodings) are not bypass-tested; the rule is a lab-grade partial. Module
binary SHA-256 090c8c02…, source modules/gabriel_batikfont_v1.rs.
Cost record
Run window 17:04:17Z → 17:04:26Z (per-CVE ledger, marginal session cost).
Evidence appendix
- Fixture:
gabriel-2026-11-11/fixtures10.py(make_batikfont, port 18328) - Evidence:
gabriel-2026-11-11/module2/evidence/batikfont-module.json - Module source:
docs/case-studies/modules/gabriel_batikfont_v1.rs
The vulnerability
Batik persists SVG font metadata without encoding, so a crafted font element
stores script content that later renders as markup. The fixture
(make_batikfont, port 18328) reproduces the delivery shape: a font upload
carrying script/event-handler markers in font metadata records a stored-XSS
mark.
The Eden patch
Tier 1 — declarative policy (blunt, fail-closed): deny every request under
/batik/font, ordinary font uploads included — false positives measured
below.
Tier 2 — native Rust module gabriel_batikfont_v1 (surgical): refuses
font uploads carrying script/event-handler markers (<script, onload=);
ordinary font uploads pass unchanged.
Measured comparison (fixtures10, run 2026-11-11)
| Probe | Baseline | Tier 1 | Tier 2 (module) | Backend effect |
|---|---|---|---|---|
| benign font upload | 200 | 403 (false positive) | 200 | none |
| attack: script in font metadata | 200 (xss_font recorded) | 403 | 403 | blocked at tier 2 |
Performance trace (Eden telemetry, live 2026-11-11)
Measured with Eden's built-in request telemetry (gateway.request.baseline
spans, read back through /api/v1/analytics/telemetry?signal=traces), not
client wall-clock. Latency Eden introduces per remediation arm for this case:
| Arm | n | mean | p50 | p95 | min–max |
|---|---|---|---|---|---|
| Tier 1 — declarative policy, blocked request (403) | 15 | 27 µs | 22 µs | 51 µs | 14 µs–51 µs |
| Tier 2 — native module, benign passes through (200) | 22 | 383 µs | 357 µs | 518 µs | 321 µs–622 µs |
| Tier 2 — native module, attack refused (403) | 14 | 138 µs | 140 µs | 195 µs | 109 µs–195 µs |
Authority lifecycle and negatives
Import 201, activation: explicit_required; publisher enroll_key, host
inventory + approve, reader inspect refused 403; tampered-statement admit
400; invalid-signature admit 403; admit prepared (not serving), activate
→ receipt serving_now, applied shards 2/2. Revoke → the identical attack
gets 503 (fail-closed); re-approve + re-activate → 403 again. All recorded
in the evidence JSON.
Honest scope
The fixture reproduces the unencoded-metadata shape, not the full Batik font
pipeline. Bypass variants (case tricks, alternate event handlers, entity
encodings) are not bypass-tested; the rule is a lab-grade partial. Module
binary SHA-256 090c8c02…, source modules/gabriel_batikfont_v1.rs.
Cost record
Run window 17:04:17Z → 17:04:26Z (per-CVE ledger, marginal session cost).