CVE-2016-2856
pt_chown in the glibc package before 2.19-18+deb8u4 on Debian jessie; the elibc package before 2...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
8.4
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.
- Record
CVE-2016-2856- CVSS 3.0
- 8.4 High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.2 High
AV:L/AC:L/Au:N/C:C/I:C/A:C - Weakness
- CWE-264
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2016-2856- Updated
- 2026-11-02
EUVDEUVD-2016-3929 No score
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.
- Record
EUVD-2016-3929- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-2wf2-64hh-9h2m
8.4
pt_chown in the glibc package before 2.19-18+deb8u4 on Debian jessie; the elibc package before 2...
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.
- Record
GHSA-2wf2-64hh-9h2m- CVSS 3.0
- 8.4 High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSV
8.4
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.
- Record
CVE-2016-2856- CVSS 3.0
- 8.4 High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2016-2856
8.4
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.
- Record
DEBIAN-CVE-2016-2856- CVSS 3.0
- 8.4 High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2016-2856
8.4
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.
- Record
UBUNTU-CVE-2016-2856- CVSS 3.0
- 8.4 High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUSN-2985-1 No score
eglibc, glibc vulnerabilities
Martin Carpenter discovered that pt_chown in the GNU C Library did not properly check permissions for tty files. A local attacker could use this to gain administrative privileges or expose sensitive information. (CVE-2013-2207, CVE-2016-2856)
Robin Hack discovered that the Name Service Switch (NSS) implementation in the GNU C Library did not properly manage its file descriptors. An attacker could use this to cause a denial of service (infinite loop). (CVE-2014-8121)
Joseph Myers discovered that the GNU C Library did not properly handle long arguments to functions returning a representation of Not a Number (NaN). An attacker could use this to cause a denial of service (stack exhaustion leading to an application crash) or possibly execute arbitrary code. (CVE-2014-9761)
Arjun Shankar discovered that in certain situations the nss_dns code in the GNU C Library did not properly account buffer sizes when passed an unaligned buffer. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2015-1781)
Sumit Bose and Lukas Slebodnik discovered that the Name Service Switch (NSS) implementation in the GNU C Library did not handle long lines in the files databases correctly. A local attacker could use this to cause a denial of service (application crash) or possibly execute arbitrary code. (CVE-2015-5277)
Adam Nielsen discovered that the strftime function in the GNU C Library did not properly handle out-of-range argument data. An attacker could use this to cause a denial of service (application crash) or possibly expose sensitive information. (CVE-2015-8776)
Hector Marco and Ismael Ripoll discovered that the GNU C Library allowed the pointer-guarding protection mechanism to be disabled by honoring the LD_POINTER_GUARD environment variable across privilege boundaries. A local attacker could use this to exploit an existing vulnerability more easily. (CVE-2015-8777)
Szabolcs Nagy discovered that the hcreate functions in the GNU C Library did not properly check its size argument, leading to an integer overflow. An attacker could use to cause a denial of service (application crash) or possibly execute arbitrary code. (CVE-2015-8778)
Maksymilian Arciemowicz discovered a stack-based buffer overflow in the catopen function in the GNU C Library when handling long catalog names. An attacker could use this to cause a denial of service (application crash) or possibly execute arbitrary code. (CVE-2015-8779)
Florian Weimer discovered that the getnetbyname implementation in the GNU C Library did not properly handle long names passed as arguments. An attacker could use to cause a denial of service (stack exhaustion leading to an application crash). (CVE-2016-3075)
- Record
USN-2985-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
glibcDebian:12 |
before 2.21-1 | 2.21-1 |
glibcDebian:13 |
before 2.21-1 | 2.21-1 |
glibcDebian:14 |
before 2.21-1 | 2.21-1 |
eglibcUbuntu:14.04:LTS |
before 2.19-0ubuntu6.8, plus listed versions 2.17-93ubuntu42.18-0ubuntu12.18-0ubuntu22.18-0ubuntu42.18-0ubuntu5 Show 13 moreShow less2.18-0ubuntu62.18-0ubuntu72.19-0ubuntu22.19-0ubuntu32.19-0ubuntu42.19-0ubuntu52.19-0ubuntu62.19-0ubuntu6.12.19-0ubuntu6.32.19-0ubuntu6.42.19-0ubuntu6.52.19-0ubuntu6.62.19-0ubuntu6.7 |
2.19-0ubuntu6.8 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| Exploit-DB | Ubuntu < 15.10 - PT Chown Arbitrary PTs Access Via User Namespace Privilege Escalation | 2016-02-22 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, Exploit-DB, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2016-2856 is a high vulnerability (CVSS 8.4) in Debian Linux, published March 13, 2016. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 1.03%, the 63rd percentile. Fixed in glibc 2.21-1.
References
halfdog.net/Security/2015/PtChownArbitraryPtsAccessViaUserNamespace
anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit?h=jessie&id=11475c083282c1582c4dd72eecfcb2b7d308c958
openwall.com/lists/oss-security/2016/03/07/2
securityfocus.com/bid/84601
ubuntu.com/usn/USN-2985-2
people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-2856.html
Show 19 moreShow less
anonscm.debian.org/cgit/pkg-glibc/glibc.git/commit?h=jessie&id=09f7764882a81e13e7b5d87d715412283a6ce403
openwall.com/lists/oss-security/2016/02/23/3
ubuntu.com/usn/USN-2985-1
nvd.nist.gov/vuln/detail/CVE-2016-2856
github.com/advisories/GHSA-2wf2-64hh-9h2m
security-tracker.debian.org/tracker/CVE-2016-2856
ubuntu.com/security/CVE-2016-2856
ubuntu.com/security/notices/USN-2985-1
cve.org/CVERecord?id=CVE-2016-2856
ubuntu.com/security/CVE-2013-2207
ubuntu.com/security/CVE-2014-8121
ubuntu.com/security/CVE-2014-9761
ubuntu.com/security/CVE-2015-1781
ubuntu.com/security/CVE-2015-5277
ubuntu.com/security/CVE-2015-8776
ubuntu.com/security/CVE-2015-8777
ubuntu.com/security/CVE-2015-8778
ubuntu.com/security/CVE-2015-8779
ubuntu.com/security/CVE-2016-3075