Out-of-bounds Read in Shadow Project

CVE-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/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.

EPSS: 0.004 (35.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 3.3 (Low). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2023-29383?
CVE-2023-29383 is a low-severity vulnerability in Shadow Project, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 3.3/10. Published 2023-04-14.
How severe is CVE-2023-29383?
Low severity. CVSS v3 base score is 3.3 out of 10.
Is CVE-2023-29383 known to be exploited?
13 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.