CVE-2016-2856
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | fixed | 2.21-1 |
| debian | bullseye | fixed | 2.21-1 |
| debian | forky | fixed | 2.21-1 |
| debian | sid | fixed | 2.21-1 |
| debian | trixie | fixed | 2.21-1 |
| debian | 8.0 | affected | |
| ubuntu | 12.04 | affected | |
| ubuntu | 14.04 | affected | |
| ubuntu | 15.10 | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| gnu | glibc | {"endIncluding":"2.18"} | |
References
- http://anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit/?h=jessie&id=09f7764882a81e13e7b5d87d715412283a6ce403
- http://anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit/?h=jessie&id=11475c083282c1582c4dd72eecfcb2b7d308c958
- http://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-2856.html
- http://www.halfdog.net/Security/2015/PtChownArbitraryPtsAccessViaUserNamespace/
- http://www.openwall.com/lists/oss-security/2016/02/23/3
- http://www.openwall.com/lists/oss-security/2016/03/07/2
- http://www.securityfocus.com/bid/84601
- http://www.ubuntu.com/usn/USN-2985-1
- http://www.ubuntu.com/usn/USN-2985-2
- https://security-tracker.debian.org/tracker/CVE-2016-2856
CWEs
CWE-264
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.