CVE-2021-3864
A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.77%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.0 HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.77% probability · 54th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-284
- Affected
- linux/linux kernel · debian/debian linux · redhat/enterprise linux
- Source
- secalert@redhat.com
References
- https://access.redhat.com/security/cve/CVE-2021-3864Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046Issue Tracking, Patch, Third Party Advisory
- 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-2021-3864Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/10/20/2Exploit, Mailing List, Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2021-3864Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2015046Issue Tracking, Patch, Third Party Advisory
- 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-2021-3864Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/10/20/2Exploit, Mailing List, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.