Vulnerability in Linux Kernel
CVE-2021-3864
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (53.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000
Affected products
- Linux Kernel
- Debian Linux — versions 10.0, 11.0
- Red Hat Enterprise Linux — versions 6.0, 7.0, 9.0
- Kernel — versions Not Known
Weakness classification (CWE)
Public proof-of-concept exploits
References
- www.openwall.com/lists/oss-security/2021/10/20/2 (Exploit, Mailing List, Third Party Advisory)
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- access.redhat.com/security/cve/CVE-2021-3864 (Third Party Advisory)
- lore.kernel.org/all/20211221021744.864115-1-longman@redhat.com/
- lore.kernel.org/lkml/20211228170910.623156-1-wander@redhat.com/
- lore.kernel.org/all/20211226150310.GA992@1wt.eu/
- security-tracker.debian.org/tracker/CVE-2021-3864 (Third Party Advisory)
Frequently asked questions
- What is CVE-2021-3864?
- CVE-2021-3864 is a high-severity vulnerability in Linux Kernel, classified under Improper Access Control. CVSS score: 7.0/10. Published 2022-08-26.
- How severe is CVE-2021-3864?
- High severity. CVSS v3 base score is 7.0 out of 10.
- Is CVE-2021-3864 known to be exploited?
- 16 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.