CVE-2021-30465

runc before 1.0.0-rc95 allows a Container Filesystem Breakout via Directory Traversal. To exploit the vulnerability, an attacker must be able to create multiple containers with a fairly specific mount configuration. The problem occurs via a symlink-exchange attack that relies on a race condition.

Published: 2021-05-27 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-30465 is rated High Risk (71.5/100): CVSS High severity, with high exploitation likelihood (EPSS 6.60%, 93th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +5.13% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-30465

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.47% 6.60% +5.13%
2 2026-05-08 2.36% 1.47% -0.89%
3 2026-05-04 — 2.36% —

Full EPSS history (37 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-30465

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.5 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 6.0 [email protected]
6.0 2.0 MEDIUM
AV:N/AC:M/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 6.4 [email protected]

Weakness enumeration for CVE-2021-30465

GitHub Security Advisory for CVE-2021-30465

GHSA-c3xm-pvg7-gh7r · Severity: high · Ecosystem: go — mount destinations can be swapped via symlink-exchange to cause mounts outside the rootfs

OS Trackers for CVE-2021-30465

vendor priority summary link
alpine high CVE-2021-30465: 2 source package rows (k3s, runc); 15 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 15, open 0. https://security.alpinelinux.org/vuln/CVE-2021-30465
debian not yet assigned CVE-2021-30465 not yet assigned priority: Debian including 1 source packages (runc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-30465
gentoo low CVE-2021-30465: 1 GLSA(s) (202107-26), 1 atom(s) (app-emulation/runc); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-30465
redhat high — https://access.redhat.com/security/cve/CVE-2021-30465
suse high CVE-2021-30465 severity important: SUSE including 299 source package names (2.0.2-4.2.20:runc-1.0.2-23.1, amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, …), 1248 product×package rows across 323 product lines (Container rancher/elemental-teal-iso/5.4, Container rancher/elemental-teal-rt/5.4, … (323 product lines)): Fixed 1081, Known Affected 148, Known Not Affected 19. https://www.suse.com/security/cve/CVE-2021-30465/
ubuntu high CVE-2021-30465 high priority: Ubuntu including 1 source packages (runc), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): released 8, DNE 1. https://ubuntu.com/security/CVE-2021-30465

Affected software / configurations for CVE-2021-30465

Vendor Product Version Raw CPE
linuxfoundation runc <= 0.1.1 cpe:2.3:a:linuxfoundation:runc:*:*:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc1:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc10:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc2:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc3:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc4:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc5:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc6:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc7:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc8:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc9:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc90:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc91:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc92:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc93:*:*:*:*:*:*
linuxfoundation runc 1.0.0 cpe:2.3:a:linuxfoundation:runc:1.0.0:rc94:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

References for CVE-2021-30465

URL Tags
http://www.openwall.com/lists/oss-security/2021/05/19/2 Mailing List Third Party Advisory
https://bugzilla.opensuse.org/show_bug.cgi?id=1185405 Issue Tracking
https://github.com/opencontainers/runc/commit/0ca91f44f1664da834bc61115a849b56d22f595f Patch Third Party Advisory
https://github.com/opencontainers/runc/releases Release Notes Third Party Advisory
https://github.com/opencontainers/runc/security/advisories/GHSA-c3xm-pvg7-gh7r Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/03/msg00023.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/35ZW6NBZSBH5PWIT7JU4HXOXGFVDCOHH/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4HOARVIT47RULTTFWAU7XBG4WY6TDDHV/
https://security.gentoo.org/glsa/202107-26 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210708-0003/ Third Party Advisory
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