HIGH
CVE-2021-35331
CWE-134Published: July 5, 2021· Updated: Jun 17, 2026
7.8
CVSS v3.1
Official Description
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
Technical Analysis
CVE-2021-35331 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected Vendors & Products
tcl1 product(s)
tcl
Source: NVD CPE · 1 total CPE entries
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (8)
→
https://core.tcl-lang.org/tcl/info/28ef6c0c741408a2Exploit · Patch · Vendor Advisory
→
https://core.tcl-lang.org/tcl/info/bad6cc213dfe8280Exploit · Vendor Advisory
→
https://github.com/tcltk/tcl/commit/4705dbdde2f32ff90420765cd93e7ac71d81a222Patch · Third Party Advisory
→
https://sqlite.org/forum/info/7dcd751996c93ec9Exploit · Third Party Advisory
→
https://core.tcl-lang.org/tcl/info/28ef6c0c741408a2Exploit · Patch · Vendor Advisory
→
https://core.tcl-lang.org/tcl/info/bad6cc213dfe8280Exploit · Vendor Advisory
→
https://github.com/tcltk/tcl/commit/4705dbdde2f32ff90420765cd93e7ac71d81a222Patch · Third Party Advisory
→
https://sqlite.org/forum/info/7dcd751996c93ec9Exploit · Third Party Advisory
Quick Facts
CVE IDCVE-2021-35331
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-134
CISA KEVNo
Affected1 vendor(s)
PublishedJul 5, 2021
Related CVEs (CWE-134)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-35331 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.