pt_chown in the glibc package before 2.19-18+deb8u4 on Debian jessie; the elibc package…
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.0 · NVD. Fix status from CNA. Impact type from CWE-264.
Summary
pt_chown in the glibc package before 2.19-18+deb8u4 on Debian jessie; the elibc package before 2.15-0ubuntu10.14 on Ubuntu 12.04 LTS and before 2.19-0ubuntu6.8 on Ubuntu 14.04 LTS; and the glibc package before 2.21-0ubuntu4.2 on Ubuntu 15.10 and before 2.23-0ubuntu1 on Ubuntu 16.04 LTS and 16.10 lacks a namespace check associated with file-descriptor passing, which allows local users to capture keystrokes and spoof data, and possibly gain privileges, via pts read and write operations, related to debian/sysdeps/linux.mk. NOTE: this is not considered a vulnerability in the upstream GNU C Library because the upstream documentation has a clear security recommendation against the --enable-pt_chown option.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:* | 12.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:* | 14.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:* | 15.10 | Vulnerable | Canonical |
| cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Debian |
| cpe:2.3:a:gnu:glibc:*:*:*:*:*:*:*:* | up to 2.18 | Running on | GNU |
- cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:* Versions 12.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:* Versions 14.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:* Versions 15.10 Vulnerable ·Canonical
- cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Debian
- cpe:2.3:a:gnu:glibc:*:*:*:*:*:*:*:* Versions up to 2.18 Running on ·GNU
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2016-2856
- 2026-10-03 Alias added: GHSA-2wf2-64hh-9h2m
References
Advisory 2
Other 6
- http://www.halfdog.net/Security/2015/PtChownArbitraryPtsAccessViaUserNamespace/
- http://anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit/?h=jessie&id=11475c083282c1582c4dd72eecfcb2b7d308c958
- [oss-security] 20160306 Re: Access to /dev/pts devices via pt_chown and user namespaces
- http://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-2856.html
- http://anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit/?h=jessie&id=09f7764882a81e13e7b5d87d715412283a6ce403
- [oss-security] 20160223 Access to /dev/pts devices via pt_chown and user namespaces
Sources
- CVE-2016-2856 · CVE Program
- CVE-2016-2856 · NVD
- FIRST EPSS
- GHSA-2wf2-64hh-9h2m · GitHub Advisory Database · CC BY 4.0
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