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No exploitation reportedFix available

CVE-2021-26957

No exploitation reported by the sources we read.

  • Published2021-02-09
  • Fixed in1.0.0
  • WeaknessCWE-125

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It has a soundness violation because there is an out-of-bounds read in xcb::xproto::change_property(), as demonstrated by a format=32 T=u8 situation where out-of-bounds bytes are sent to an X server.

Timeline

dates in UTC
  1. 2021-02-0923:15CVE publishedNVD

Versions per branch

OSV · NVD
xcb
BranchAffectedFixed in
1.0≥ 0.0.0-0, < 1.0.01.0.0
1.0< 1.0.01.0.0
Xcb project xcb
BranchAffectedFixed in
2021.x≤ 2021-02-04no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • rust-xcbUbuntu:22.04:LTSall versions · no fixed version listed
  • rust-xcbDebian:14all versions · fixed in 1.1.1-1
  • rust-xcbDebian:13all versions · fixed in 1.1.1-1
  • rust-xcbDebian:12all versions · fixed in 1.1.1-1

Full record on NVD

Fix

  1. Update xcb to 1.0.0

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • NVDweakness (CWE)CWE-125read 2026-10-23
  • FIRST EPSSEPSS score1.7 %2026-11-08
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryCRITICAL2021-08-19

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-02-09
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-2xpg-3hx4-fm9r GHSA-3288-cwgw-ch86 GHSA-3cj3-jrrp-9rxf GHSA-mp6r-fgw2-rxfx

Frequently asked questions

What is CVE-2021-26957?

An issue was discovered in the xcb crate through 2021-02-04 for Rust. It has a soundness violation because there is an out-of-bounds read in xcb::xproto::change_property(), as demonstrated by a format=32 T=u8 situation where out-of-bounds bytes are sent to an X server.

Is CVE-2021-26957 actively exploited?

Active exploitation of CVE-2021-26957 has not been confirmed. Its EPSS score was 1.7% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-26957?

CVE-2021-26957 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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