Information disclosure via oversized realpath result
Published Aug 24, 2022 · Updated Jun 9, 2025
Information disclosure in GNU C Library 2.33 through 2.34 allows local users to expose process memory through an overlong path. The realpath() implementation returns a newly allocated buffer instead of the caller-supplied resolved buffer when the result exceeds PATH_MAX, leaving the expected buffer uninitialized. A local user must trigger an affected program that uses the untouched caller buffer; a demonstrated SUID fusermount path exposes stack pointers.
Summary
What happened
Information disclosure in GNU C Library 2.33 through 2.34 allows local users to expose process memory through an overlong path. The realpath() implementation returns a newly allocated buffer instead of the caller-supplied resolved buffer when the result exceeds PATH_MAX, leaving the expected buffer uninitialized. A local user must trigger an affected program that uses the untouched caller buffer; a demonstrated SUID fusermount path exposes stack pointers.
The record
- CVE
- CVE-2021-3998
- Published
- Aug 24, 2022
- Updated
- Jun 9, 2025
- Vendor
- GNU
- Product
- GNU C Library (glibc)
- Classifications
- CWE-252, CWE-125
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Aug 24, 2022CVE publishedPublication date reported by the CVE source.
- Jun 9, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=Affects glibc v2.33 and above.
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Qualys fusermount information-disclosure proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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