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CVE-2021-29939

23
FAUCET Score

CVE-2021-29939 describes an out-of-bounds write vulnerability in the Rust stackvector crate, specifically affecting versions through 2021-02-19, due to anomalous data provided by size_hint during a StackVec::extend operation. This vulnerability carries a CVSS score of 7.3 (HIGH), indicating it can be exploited remotely with low attack complexity, potentially leading to low impact on confidentiality, integrity, and availability. Currently, there is no evidence of active exploitation, no public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage, suggesting a low immediate threat.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.0.9CPE matchmatch criteria
cpe:2.3:a:stackvector_project:stackvector:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

7.3HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
3.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.03%
Probability of exploitation in next 30 days
EPSS Percentile
60.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0103 is in the 37th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

rustpatch availablevia ghsa
Product: stackvectorFixed in: 1.0.9

Vendor Advisories (1)

rustGHSA-9frf-r7c7-j2vghigh

Out of bounds write in stackvector

Aug 25, 2021

References

rustsec.org / advisories/RUSTSEC-2021-0048.html
ExploitVendor Advisory