CVE-2021-29136

Open Container Initiative umoci before 0.4.7 allows attackers to overwrite arbitrary host paths via a crafted image that causes symlink traversal when "umoci unpack" or "umoci raw unpack" is used.

Published: 2021-04-06 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]

NVD Status：Modified，CVE State: published

View at NVD, CVE.org, EUVD

Threat Intelligence & Risk Assessment for CVE-2021-29136

EPSS CVSS CWE GHSA Affected OS Tracker

Conclusion & alert: CVE-2021-29136 is rated Low Risk (31.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.34%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-29136

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	0.15%	0.34%	+0.20%
2	2025-03-30	0.17%	0.15%	-0.03%
3	2025-03-29	—	0.17%	—

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-29136

CVSS metrics for this CVE.

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. 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:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	1.8	3.6	[email protected]
2.1	2.0	LOW	`AV:L/AC:L/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:L) Requires local access to the target system. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	3.9	2.9	[email protected]

Weakness enumeration for CVE-2021-29136

CWE-20 MITRE ↗

GitHub Security Advisory for CVE-2021-29136

GHSA-9m95-8hx6-7p9v · Severity: medium · Ecosystem: go — Improper input validation in umoci

OS Trackers for CVE-2021-29136

vendor	priority	summary	link
`alpine`	medium	CVE-2021-29136: 2 source package rows (singularity, umoci); 20 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 20, open 0.	https://security.alpinelinux.org/vuln/CVE-2021-29136
`debian`	not yet assigned	CVE-2021-29136 not yet assigned priority: Debian including 1 source packages (umoci), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2021-29136
`suse`	high	CVE-2021-29136 severity important: SUSE including 8 source package names (singularity-3.7.4-bp152.2.24.1, singularity-3.7.4-bp153.2.3.1, …), 25 product×package rows across 23 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (23 product lines)): Fixed 25.	https://www.suse.com/security/cve/CVE-2021-29136/
`ubuntu`	medium	CVE-2021-29136 medium priority: Ubuntu including 1 source packages (umoci), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 6, ignored 4, DNE 3, needed 2, released 1.	https://ubuntu.com/security/CVE-2021-29136

Affected software / configurations for CVE-2021-29136

Vendor	Product	Version	Raw CPE
linuxfoundation	umoci	< 0.4.7	cpe:2.3:a:linuxfoundation:umoci::::::::
sylabs	singularity	< 3.7.3	cpe:2.3:a:sylabs:singularity::::::::

References for CVE-2021-29136

URL	Tags
http://www.openwall.com/lists/oss-security/2021/04/06/2	Mailing List Patch Third Party Advisory
https://github.com/opencontainers/umoci/commit/d9efc31daf2206f7d3fdb839863cf7a576a2eb57	Patch Third Party Advisory
https://github.com/opencontainers/umoci/security/advisories/GHSA-9m95-8hx6-7p9v	Third Party Advisory

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