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CVE-2021-25900

28
FAUCET Score

CVE-2021-25900 is a critical heap-based buffer overflow vulnerability (CWE-787) affecting the smallvec crate in Rust, specifically versions prior to 0.6.14 and 1.x prior to 1.6.1, as well as the Servo project. This flaw, rated 9.8 CRITICAL (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), allows unauthenticated attackers to achieve high impact on confidentiality, integrity, and availability with low attack complexity. Despite its severity, there is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 0.6.3, < 0.6.14CPE matchmatch criteria
cpe:2.3:a:servo:smallvec:*:*:*:*:*:rust:*:*
>= 1.0.0, < 1.6.1CPE matchmatch criteria
cpe:2.3:a:servo:smallvec:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.67%
Probability of exploitation in next 30 days
EPSS Percentile
74.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0167 is in the 62nd percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

rustpatch availablevia ghsa
Product: smallvecFixed in: 0.6.14
rustpatch availablevia ghsa
Product: smallvecFixed in: 1.6.1

Vendor Advisories (1)

rustGHSA-43w2-9j62-hq99critical

Buffer overflow in SmallVec::insert_many

May 24, 2022

References

rustsec.org / advisories/RUSTSEC-2021-0003.html
ExploitPatchThird Party Advisory