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CVE-2021-26957

29
FAUCET Score

CVE-2021-26957 is a critical out-of-bounds read vulnerability affecting the xcb crate for Rust, specifically within the xcb::xproto::change_property() function. This flaw allows an unauthenticated attacker to send specially crafted data to an X server, potentially leading to severe consequences. With a CVSS score of 9.8, it poses a critical risk, enabling full compromise of confidentiality, integrity, and availability. Currently, there is no public exploit code available, nor is there evidence of active exploitation 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

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
1.75%
Probability of exploitation in next 30 days
EPSS Percentile
75.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0175 is in the 64th 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 (1)

rustpatch availablevia ghsa
Product: xcbFixed in: 1.0.0

Vendor Advisories (1)

rustGHSA-2xpg-3hx4-fm9rcritical

Out of bounds read in xcb

Aug 25, 2021

References

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