CVE-2023-29383
In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (change finger).
Published Apr 14, 2023 · updated Oct 14, 2026 · shadow project shadow
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.
Code
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Timeline
Detection, updates, and resolution for this record.
Apr 14, 2023 · NIST NVD
Detected
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
Oct 14, 2026 · NIST NVD
Updated
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
Affected
- cpe shadow project/shadow4.13
Sources
- CVE.orgVulnerability recordCVE-2023-29383
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2023-29383
30-day exploitation probability 0.4%
first.org - NIST NVDVulnerability recordCVE-2023-29383
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
nvd.nist.gov