Incomplete blacklist vulnerability in the chfn function in libuser before 0.56.13-8 and 0.60 before 0.60-7, as used in the userhelper progra
Incomplete blacklist vulnerability in the chfn function in libuser before 0.56.13-8 and 0.60 before 0.60-7, as used in the userhelper program in the usermode package, allows local users to cause a denial of service (/etc/passwd corruption) via a newline character in the GECOS field.
- Published
- Aug 11, 2015
- Updated
- Jun 16, 2026
- EPSS
- 5.3% · 92th percentile
- CWE
- CWE-20
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Report tools
Action score
10
Monitor
Low priority for now.
- CVSS
- 8 / 40 · 2.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 2 / 30 · 5.3%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| redhat | libuser | cpe:2.3:a:redhat:libuser |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- redhat libuserup to 0.56.13-5 inclusive
- redhat libuser0.60-1
- redhat libuser0.60-2
- redhat libuser0.60-3
- redhat libuser0.60-4
- redhat libuser0.60-5
- redhat libuser0.60-6
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | libuser | before 1:0.62~dfsg-0.1 | 1:0.62~dfsg-0.1 |
| Debian:7 | libuser | before 1:0.56.9.dfsg.1-1.2+deb7u1 | 1:0.56.9.dfsg.1-1.2+deb7u1 |
| Red Hat:enterprise_linux:6::client | libuser | before 0:0.56.13-8.el6_7 | 0:0.56.13-8.el6_7 |
| Red Hat:enterprise_linux:6::client | libuser-debuginfo | before 0:0.56.13-8.el6_7 | 0:0.56.13-8.el6_7 |
| Red Hat:enterprise_linux:6::client | libuser-devel | before 0:0.56.13-8.el6_7 | 0:0.56.13-8.el6_7 |
| Red Hat:enterprise_linux:6::client | libuser-python | before 0:0.56.13-8.el6_7 | 0:0.56.13-8.el6_7 |
| Red Hat:enterprise_linux:7::client | libuser | before 0:0.60-7.el7_1 | 0:0.60-7.el7_1 |
| Red Hat:enterprise_linux:7::client | libuser-debuginfo | before 0:0.60-7.el7_1 | 0:0.60-7.el7_1 |
| Red Hat:enterprise_linux:7::client | libuser-devel | before 0:0.60-7.el7_1 | 0:0.60-7.el7_1 |
| Red Hat:enterprise_linux:7::client | libuser-python | before 0:0.60-7.el7_1 | 0:0.60-7.el7_1 |
| Red Hat:enterprise_linux:7::server | libuser | before 0:0.60-7.ael7b_1 | 0:0.60-7.ael7b_1 |
| Red Hat:enterprise_linux:7::server | libuser-debuginfo | before 0:0.60-7.ael7b_1 | 0:0.60-7.ael7b_1 |
| Red Hat:enterprise_linux:7::server | libuser-devel | before 0:0.60-7.ael7b_1 | 0:0.60-7.ael7b_1 |
| Red Hat:enterprise_linux:7::server | libuser-python | before 0:0.60-7.ael7b_1 | 0:0.60-7.ael7b_1 |
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:libuser | 1:0.62~dfsg-0.1 · Debian:12 | Package registry (OSV) |
| red hat:libuser | 0:0.56.13-8.el6_7 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libuser-debuginfo | 0:0.56.13-8.el6_7 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libuser-devel | 0:0.56.13-8.el6_7 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:libuser-python | 0:0.56.13-8.el6_7 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Metasploit module ×1
- Exploit-DB entry ×3
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | dos | 2015-07-27 |
| Exploit-DB entry | local | 2018-05-16 |
| Exploit-DB entry | local | 2018-05-16 |
| Metasploit module | exploit/linux/local/libuser_roothelper_priv_escLibuser roothelper Privilege Escalationexploit | 2015-07-24 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Metasploit-18 d
- First PoC-15 d
- Published
- TodaySep 30, 2026+4068 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- P
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
AV:L/AC:L/Au:N/C:N/I:N/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for helpChange log
- Fix✗ → ✓
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References
- lists.fedoraproject.org/pipermail/package-announce/2015-August/163044.html
- lists.fedoraproject.org/pipermail/package-announce/2015-July/162947.html
- rhn.redhat.com/errata/RHSA-2015-1482.html
- rhn.redhat.com/errata/RHSA-2015-1483.html
- www.securityfocus.com/bid/76021
- www.securitytracker.com/id/1033040
- access.redhat.com/articles/1537873
- www.exploit-db.com/exploits/44633/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.