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Not in CISA KEV
CRITICAL severity

Unchecked Return Value in xcbGHSA-3288-cwgw-ch86

CRITICAL

GHSA-3288-cwgw-ch86 is a critical-severity (CVSS 9.8) CWE-252 vulnerability in xcb. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for xcb — see the affected versions and patch details below.

Also known asCVE-2021-26955CVE-2021-26956CVE-2021-26957CVE-2021-26958GHSA-2xpg-3hx4-fm9rGHSA-3cj3-jrrp-9rxf
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.7%probability of exploitation in next 30 days
Lower Risk+0.02%
Lower risk than most CVEs78th percentile — riskier than 78% of all scored CVEsHighest risk
0.00%0.75%1.50%2.25%0.5%1.7%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🦀xcb

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It has a soundness violation because xcb::xproto::GetAtomNameReply::name() calls std::str::from_utf8_unchecked() on unvalidated bytes from an X server.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.ioxcball versions1.0.0cargo update -p xcb --precise 1.0.0

Affected Products

1 product · 1 configurations
Application
xcbxcb_project
≤ 2021-02-04
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It…

rustsec.orgNVDFeb 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for xcb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update xcb to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3288-cwgw-ch86 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It has a soundness violation because xcb::xproto::GetAtomNameReply::name() calls std::str::from_utf8_unchecked() on unvalidated bytes from an X server.
O3 Security · Impact-Aware SCA

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Unchecked Return Value in xcb (Critical 9.8)