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CVE-2021-26958

26
FAUCET Score

CVE-2021-26958 is a high-severity soundness violation affecting the xcb crate for Rust, specifically versions through 2021-02-04. This vulnerability allows for type confusion due to improper use of std::mem::transmute after xcb::base::cast_event, potentially leading to arbitrary type transmutation. With a CVSS score of 8.8 (High), it presents a significant risk with high impact on confidentiality, integrity, and availability, and can be exploited remotely with low privileges and no user interaction. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2021-02-04CPE matchmatch criteria
cpe:2.3:a:xcb_project:xcb:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.60%
Probability of exploitation in next 30 days
EPSS Percentile
73.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0160 is in the 71st percentile among its peer group of 17,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 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: xcbFixed in: 1.0.0

Vendor Advisories (1)

rustGHSA-3cj3-jrrp-9rxfhigh

Unchecked Return Value in xcb

Aug 25, 2021

References

rustsec.org / advisories/RUSTSEC-2021-0019.html
ExploitVendor Advisory