TI-2023-13773 Aliases CVE-2023-29383 GHSA-p9w4-8hh8-crcx

In Shadow 4.13, it is possible to inject control characters into fields provided to the…

MEDIUM 49CWE-125Published 2023-04-14 · Updated 2026-10-14

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · Low · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (change finger). Although it is not possible to exploit this directly (e.g., adding a new user fails because \n is in the block list), it is possible to misrepresent the /etc/passwd file when viewed. Use of \r manipulations and Unicode characters to work around blocking of the : character make it possible to give the impression that a new user has been added. In other words, an adversary may be able to convince a system administrator to take the system offline (an indirect, social-engineered denial of service) by demonstrating that "cat /etc/passwd" shows a rogue user account.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00426 37th percentileScored 2026-11-07

Public exploit Yes 2 exploit referencesTagged by NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

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 · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:shadow_project:shadow:4.13:::::::*	4.13	Vulnerable	Shadow Project

cpe:2.3:a:shadow_project:shadow:4.13:*:*:*:*:*:*:* Versions 4.13 Vulnerable ·Shadow Project

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 4 products

Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9

Timeline

2026-10-02 Threatist record created from CVE-2023-29383
2026-10-03 Alias added: GHSA-p9w4-8hh8-crcx

References

Exploit 2

Patch 1

https://github.com/shadow-maint/shadow/commit/e5905c4b84d4fb90aefcd96ee618411ebfac663d

Other 1

https://github.com/shadow-maint/shadow/pull/687

TI-2017-09165 In shadow before 4.5, the newusers tool could be made to manipulate internal data… CVSS 3.1CRITICAL 9.8
TI-2019-14333 shadow 4.8, in certain circumstances affecting at least Gentoo, Arch Linux, and Void… CVSS 3.1HIGH 7.8
TI-2016-05355 Integer overflow in shadow 4.2.1 allows local users to gain privileges via crafted input to newuidmap. CVSS 3.0HIGH 7.8
TI-2018-05191 An issue was discovered in shadow 4.5. CVSS 3.0MEDIUM 5.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences