CVE-2021-35331

Exp

In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file. NOTE: multiple third parties dispute the significance of this finding

Published: 2021-07-05 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-35331 is rated High Exploit Risk (73/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.64%). 3 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.15% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-35331

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-35331

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.49% 1.64% +1.15%
2 2026-06-12 0.29% 0.49% +0.20%
3 2026-02-01 — 0.29% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-35331

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2021-35331

OS Trackers for CVE-2021-35331

vendor priority summary link
alpine — CVE-2021-35331: 1 source package rows (tcl); 1 state rows across 1 repos (edge-main); fixed 1, open 0. https://security.alpinelinux.org/vuln/CVE-2021-35331
debian unimportant CVE-2021-35331 unimportant priority: Debian including 1 source packages (tcl8.6), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2021-35331
ubuntu negligible CVE-2021-35331 negligible priority: Ubuntu including 1 source packages (tcl8.6), 12 status rows across 12 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, trusty, upstream, xenial): not-affected 6, ignored 4, DNE 1, needs-triage 1. https://ubuntu.com/security/CVE-2021-35331

Affected software / configurations for CVE-2021-35331

Vendor Product Version Raw CPE
tcl tcl 8.6.11 cpe:2.3:a:tcl:tcl:8.6.11:*:*:*:*:*:*:*

References for CVE-2021-35331

cvelogic Threat Intelligence