vulnerability / NVI-00017805 / Revision 1
Scriban: ExpressionDepthLimit guard is non-enforcing — parser-recursion DoS in 6.6.0–7.2.0 (incomplete fix for GHSA-wgh7-7m3c-fx25 / GHSA-p6q4-fgr8-vx4p)
GitHub lists this reviewed advisory for Scriban, Scriban.Signed. 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.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Scriban
source listed>= 6.6.0, <= 7.2.0
### Summary The `ExpressionDepthLimit` parser guard in Scriban does not actually stop parsing — it only logs a non-fatal error and lets recursive descent continue. As a result, a template containing a deeply nested expression (parentheses, array initializers, object initializers, or unary operators) drives the recursive-descent parser into a native stack overflow. The resulting `StackOverflowException` is **uncatchable** in .NET and **immediately terminates the host process**. Any application that parses an attacker-influenced template — or that passes attacker-controlled strings to `object.eval` / `object.eval_template` — can be crashed by a single small request (roughly an 8 KB payload). This is a denial-of-service. It affects both Scriban-native (`Template.Parse`) and Liquid (`Template.ParseLiquid`) syntax modes, which share the same expression parser. This re-opens two advisories that were reported as fixed: **GHSA-wgh7-7m3c-fx25** ("Uncontrolled recursion in parser → StackOverflow", reported fixed in 6.6.0) and **GHSA-p6q4-fgr8-vx4p** ("StackOverflow via nested array initializers bypasses ExpressionDepthLimit", reported fixed in 7.0.0). Both fixes are incomplete: the limit
Scriban.Signed
source listed>= 6.6.0, <= 7.2.0
### Summary The `ExpressionDepthLimit` parser guard in Scriban does not actually stop parsing — it only logs a non-fatal error and lets recursive descent continue. As a result, a template containing a deeply nested expression (parentheses, array initializers, object initializers, or unary operators) drives the recursive-descent parser into a native stack overflow. The resulting `StackOverflowException` is **uncatchable** in .NET and **immediately terminates the host process**. Any application that parses an attacker-influenced template — or that passes attacker-controlled strings to `object.eval` / `object.eval_template` — can be crashed by a single small request (roughly an 8 KB payload). This is a denial-of-service. It affects both Scriban-native (`Template.Parse`) and Liquid (`Template.ParseLiquid`) syntax modes, which share the same expression parser. This re-opens two advisories that were reported as fixed: **GHSA-wgh7-7m3c-fx25** ("Uncontrolled recursion in parser → StackOverflow", reported fixed in 6.6.0) and **GHSA-p6q4-fgr8-vx4p** ("StackOverflow via nested array initializers bypasses ExpressionDepthLimit", reported fixed in 7.0.0). Both fixes are incomplete: the limit
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. GitHub Advisory 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.
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-6q7j-xr26-3h2c ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.