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)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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.evaltemplate — 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)…

Published by the source

26 Jun 2026, 21:02 UTC

Last modified by the source

6 Jul 2026, 13:10 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6q7j-xr26-3h2c

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# Patch Next advisory brief: GHSA-6q7j-xr26-3h2c

Advisory: 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)
IDs: GHSA-6q7j-xr26-3h2c
Record: https://patchnext.com/advisories/ghsa-6q7j-xr26-3h2c (revision 1, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: scriban.signed 7.2.1; scriban 7.2.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet scriban.signed: affected >= 6.6.0, <= 7.2.0; fixed in 7.2.1
- NuGet scriban: affected >= 6.6.0, <= 7.2.0; fixed in 7.2.1

## Suggested inspection (read-only)
- NuGet scriban.signed: check the installed version with your package manager.
- NuGet scriban: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on scriban.signed, scriban.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6q7j-xr26-3h2c (GitHub-reviewed advisory GHSA-6q7j-xr26-3h2c lists affected ranges: NuGet scriban >=6.6.0 =6.6.0 <=7.2.0)

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