CVE-2021-3864
What it is
A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.8% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.8% in the next 30 days (EPSS).
- Severity: 7.0 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.8% · EPSS, next 30 days
- Weakness
- CWE-284 · Improper access control
- Record status
- Modified
Affected
- Linux Kernel
- Debian Linux 10.0
- Debian Linux 11.0
- Redhat Enterprise Linux 6.0
- Redhat Enterprise Linux 7.0
- Redhat Enterprise Linux 9.0
Attack profile CVSS 3.1 · 7.0
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-3864.md and follow it. Check whether this project is affected by CVE-2021-3864. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046
References
- https://access.redhat.com/security/cve/CVE-2021-3864
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046
- https://lore.kernel.org/all/20211221021744.864115-1-longman%40redhat.com/
- https://lore.kernel.org/all/20211226150310.GA992%401wt.eu/
- https://lore.kernel.org/lkml/20211228170910.623156-1-wander%40redhat.com/
- https://security-tracker.debian.org/tracker/CVE-2021-3864
- https://www.openwall.com/lists/oss-security/2021/10/20/2
- https://access.redhat.com/security/cve/CVE-2021-3864
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046
- https://lore.kernel.org/all/20211221021744.864115-1-longman%40redhat.com/
- https://lore.kernel.org/all/20211226150310.GA992%401wt.eu/
- https://lore.kernel.org/lkml/20211228170910.623156-1-wander%40redhat.com/
- https://security-tracker.debian.org/tracker/CVE-2021-3864
- https://www.openwall.com/lists/oss-security/2021/10/20/2