vulnerability / NVI-00014057 / Revision 2
Kestra: SSRF via Pebble http() function allows unauthenticated access to internal services & cloud metadata
GitHub lists this reviewed advisory for io.kestra:core, io.kestra:kestra-core. 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.
8.6 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.406%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.35083. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
io.kestra:core
source listed<= 1.3.31
### Summary The Pebble template engine's `http()` function in Kestra OSS accepts user-controlled URLs without any validation, allowing Server-Side Request Forgery (SSRF) attacks. An unauthenticated attacker can import a malicious Flow YAML and execute it to access internal services, cloud metadata endpoints (AWS 169.254.169.254), or localhost services. The vulnerability affects all Kestra OSS deployments with default configuration. ### Details The root cause is in `core/src/main/java/io/kestra/core/runners/pebble/functions/HttpFunction.java` (lines 77-106): 1. **No URL validation**: User input is passed directly to `URI.create()` with no checks for private IPs, internal hosts, or restricted schemes 2. **No IP filtering**: Missing checks for 10.0.0.0/8, 192.168.0.0/16, 169.254.169.254, 127.0.0.1 3. **No scheme restriction**: `file://`, `gopher://` schemes are not blocked 4. **No authentication required**: `TenantValidationFilter.java` only checks tenant == "main" — no authentication 5. **Unconditional registration**: `HttpFunction` is registered without any feature flags in `Extension.java:180` ### PoC **Prerequisites:** ```bash docker run -d --name kestra-ssrf -p 8080:8080 kestr
io.kestra:kestra-core
source listed< 2.0.0
### Summary The Pebble template engine's `http()` function in Kestra OSS accepts user-controlled URLs without any validation, allowing Server-Side Request Forgery (SSRF) attacks. An unauthenticated attacker can import a malicious Flow YAML and execute it to access internal services, cloud metadata endpoints (AWS 169.254.169.254), or localhost services. The vulnerability affects all Kestra OSS deployments with default configuration. ### Details The root cause is in `core/src/main/java/io/kestra/core/runners/pebble/functions/HttpFunction.java` (lines 77-106): 1. **No URL validation**: User input is passed directly to `URI.create()` with no checks for private IPs, internal hosts, or restricted schemes 2. **No IP filtering**: Missing checks for 10.0.0.0/8, 192.168.0.0/16, 169.254.169.254, 127.0.0.1 3. **No scheme restriction**: `file://`, `gopher://` schemes are not blocked 4. **No authentication required**: `TenantValidationFilter.java` only checks tenant == "main" — no authentication 5. **Unconditional registration**: `HttpFunction` is registered without any feature flags in `Extension.java:180` ### PoC **Prerequisites:** ```bash docker run -d --name kestra-ssrf -p 8080:8080 kestr
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. FIRST EPSS
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.
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-r56g-q4p6-m3p6 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-73247 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.