CVE-2021-26955 json
Unchecked Return Value in xcb
published 2021-02-04 5 y ago modified 2026-06-17 4 mo ago also CVE-2021-26956 , CVE-2021-26957 , CVE-2021-26958 , GHSA-2xpg-3hx4-fm9r , GHSA-3288-cwgw-ch86 , GHSA-3cj3-jrrp-9rxf , GHSA-mp6r-fgw2-rxfx , RUSTSEC-2021-0019 , EUVD-2021-1523
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.7%
- EPSS 1.7% chance of exploitation in 30 days, percentile 77%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- crates.io xcb 1.0.0
- rust-xcb Debian 14, Debian 13, Debian 12 1.1.1-1
debian advisories DEBIAN-CVE-2021-26955
Exploit prediction
1.75% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- rustsec.org https://rustsec.org/advisories/RUSTSEC-2021-0019.html referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | xcb | <1.0.0 >=0.0.0-0, <1.0.0 |
1.0.0 |
Classification
References
-
rustsec.org
/advisories/RUSTSEC-2021-0019.html
web, exploit, vendor-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-26955
advisory
-
github.com
/RustSec/advisory-db/issues/653
web, report
-
github.com
/rtbo/rust-xcb
package
-
nvd.nist.gov
/vuln/detail/CVE-2021-26958
advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-26956
advisory
-
github.com
/rust-x-bindings/rust-xcb/issues/95
web, report
-
nvd.nist.gov
/vuln/detail/CVE-2021-26957
advisory
-
crates.io
/crates/xcb
package
-
github.com
/rust-x-bindings/rust-xcb/issues/78
report
-
github.com
/rust-x-bindings/rust-xcb/issues/94
report
-
github.com
/rust-x-bindings/rust-xcb/issues/96
report
Sources
- CVE List CVE-2021-26955
- GitHub Advisory GHSA-3288-cwgw-ch86
- GitHub Advisory GHSA-3cj3-jrrp-9rxf
- GitHub Advisory GHSA-mp6r-fgw2-rxfx
- GitHub Advisory GHSA-2xpg-3hx4-fm9r
- NVD CVE-2021-26955
- OSV RUSTSEC-2021-0019
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.