Cyber Resilience

CVE-2021-26120

RCE in Debian Linux 10.0 … 9.0

High EPSSRCE
Published
22 February 2021
Modified
21 November 2024
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.82 99.6th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2021-26120 is a critical-severity Code Injection (CWE-94) vulnerability in Debian Debian Linux. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 0.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Smarty before 3.1.39 allows code injection via an unexpected function name after a {function name= substring.

CWE(s)

Related Threats

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1059 Command and Scripting Interpreter Executionconfidence: HIGH
The vulnerability allows arbitrary code injection via template function names, directly enabling command/script execution.
T1203 Exploitation for Client Execution Executionconfidence: MEDIUM
Code injection through a template can be triggered by client-side exploitation when a crafted template is processed.
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2018-7602Same product: Debian Debian Linux
CVE-2020-8163Same product: Debian Debian Linux
CVE-2009-1151Same product: Debian Debian Linux
CVE-2017-7494Same product: Debian Debian Linux
CVE-2019-0193Same product: Debian Debian Linux
CVE-2024-0755Same product: Debian Debian Linux
CVE-2020-8518Same product: Debian Debian Linux
CVE-2021-22204Same product: Debian Debian Linux
CVE-2023-50447Same product: Debian Debian Linux
CVE-2024-13861Same product: Debian Debian Linux

Affected Assets

smarty
smarty
≤ 3.1.39
debian
debian linux
10.0, 11.0, 9.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.3.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Validates inputs used in dynamic code generation to block injected directives.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

PR.PS-06's SDLC practices directly target injection flaws via secure coding and testing (mostly), yet as a single broad outcome it leaves many code-generation specifics unaddressed (partial).

PR.DS-10 none match
prevents

PR.DS-10 protects runtime data confidentiality/integrity but has no bearing on neutralizing externally influenced input during code generation, so neither direction shows any preventive effect.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Banning unapproved code samples and unauthenticated web services, combined with secure-coding standards and SAST, prevents the dynamic generation or inclusion of attacker-supplied code.

none

Controls that restrict unauthorized or malicious code from being introduced via external networks or removable media limit opportunities for an attacker to inject and execute arbitrary code.

References