# CVE-2026-124437: Scriban before 7.5.3 Denial of Service via Unguarded Builtins and Recursion

Status: published. Published: 2026-11-08. Updated: 2026-11-13.

Scriban before 7.5.3 contains a resource exhaustion vulnerability that allows untrusted template authors to exhaust memory and CPU because builtins like math.format, regex.replace and string.escape skip the LimitToString allocation guard. Attackers can submit small templates using huge format precision specifiers, shared-structure array comparison, BigInteger multiplication or exponential function recursion that ignore LoopLimit and CancellationToken, crashing or stalling multi-tenant hosts.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- scriban / scriban (Scriban): ≥ 0; < 7.5.3 (affected, semver); 7.5.3 (unaffected, semver). Source: CNA: VulnCheck
- scriban / scriban (Scriban.Signed): ≥ 0; < 7.5.3 (affected, semver); 7.5.3 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.41% as of 2026-11-12; percentile 36.30%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-400

## Exploit evidence

- exploit: https://github.com/scriban/scriban/security/advisories/GHSA-95w2-9mjq-6c74 (ADP: CISA-ADP)

## References

- https://github.com/scriban/scriban/security/advisories/GHSA-95w2-9mjq-6c74 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/scriban-before-7.5.3-denial-of-service-via-unguarded-builtins-and-recursion (CNA: VulnCheck; third-party-advisory)

- https://github.com/scriban/scriban/security/advisories/GHSA-95w2-9mjq-6c74 (ADP: CISA-ADP; exploit)

- https://github.com/scriban/scriban/security/advisories/GHSA-95w2-9mjq-6c74 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/scriban-before-7.5.3-denial-of-service-via-unguarded-builtins-and-recursion (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-124437; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124437; retrieved 2026-11-13; source updated 2026-11-12

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-124437; retrieved 2026-11-13; source updated Not reported

Revision: 0d8fb2e443bcd3aad759b5dab01e546fe6e0c5db63957e9563e76503b4375e11

Canonical: https://y2.dev/cve/CVE-2026-124437

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