VulnerabilityPublished 1 Jul 2026

CVE-2026-41579: opencontainers runc · UNIX Symbolic Link (Symlink) Following

Affects opencontainers runcSource CVE Database V5

Compare

Not known to be exploited · CVSS 3.3 Low · fixed in 1.5.0-rc.3 : update opencontainers runc when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score

3.3Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.5.0-rc.3, 1.4.3, 1.3.6 +1

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade runc to 1.5.0-rc.3, 1.4.3 or 1.3.6; opencontainers/runc to 1.5.0, 1.4.3 or 1.3.6.

Affected software

Product	Affected	Fixed in
opencontainersrunc	Affected >=1.5.0-rc.1 <1.5.0-rc.3	Fixed in 1.5.0-rc.3
opencontainersrunc	Affected >=1.4.0-rc.1 <1.4.3	Fixed in 1.4.3
opencontainersrunc	Affected <1.3.6	Fixed in 1.3.6
GitHubopencontainers/runc`pkg:github/opencontainers/runc`Other threats	Affected <1.3.6 <1.4.3 <1.5.0	Fixed in 1.3.6 1.4.3 1.5.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade runc to version 1.3.6, 1.4.3, 1.5.0 or later, where this vulnerability has been fixed. If using Docker, this issue is not exploitable due to Docker's top-level read-only layer. For other container runtimes built on runc, ensure they use patched runc versions or apply equivalent mitigations to prevent symlink-based host filesystem manipulation.

Description

runc is a CLI tool for spawning and running containers according to the OCI specification. In versions prior to 1.3.6, 1.4.0-rc.1, 1.4.0-rc.12, 1.5.0-rc.1, and 1.5.0-rc.1, when setting up the container rootfs, setupPtmx and setupDevSymlinks call os.Remove and os.Symlink with a filepath.Join string which allow an image with /dev as a symlink to trick runc into deleting files called ptmx on the host or creating a hardcoded set of symlinks with specific names and targets in an arbitrary pre-existing host directory. This issue is not exploitable under Docker, because Docker creates a top-level read-only layer that masks any malicious /dev symlink present in the container image — unlike some other Linux container tooling, whose higher-level runtimes built on runc remain exposed to exploitation via a malicious image. This issue has been fixed in versions 1.3.6, 1.4.3 and 1.5.0.

Impact

The vulnerability allows a container image to manipulate host filesystem objects by exploiting symlink handling during container rootfs setup. This can lead to unauthorized deletion or creation of files on the host, impacting host integrity. However, the impact is limited as it requires local access (attack vector is local), user interaction, and low privileges, and it does not affect confidentiality or availability. Docker users are not affected due to its protective layering.

Summary

In opencontainers runc versions before 1.3.6, 1.4.3, and 1.5.0, the setupPtmx and setupDevSymlinks functions use os.Remove and os.Symlink on paths constructed with filepath.Join. If a container image contains /dev as a symlink, this can trick runc into deleting host files named ptmx or creating symlinks with specific names and targets in arbitrary existing host directories. Docker mitigates this by applying a top-level read-only layer that masks malicious /dev symlinks, but other container runtimes built on runc may remain vulnerable. The issue is tracked as CVE-2026-41579 and classified under CWE-61 (Improper Handling of Symbolic Links).

CWE-61UNIX Symbolic Link (Symlink) Following (opens in a new tab)
Compound weaknessLikelihood of exploit: HighOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
Implementation
Symbolic link attacks often occur when a program creates a tmp directory that stores files/links. Access to the directory should be restricted to the program as to prevent attackers from manipulating the files.
Architecture and Design · Separation of Privilege
Follow the principle of least privilege when assigning access rights to entities in a software system.
OWASP Cheat Sheets
Authorization (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Jul 2026, 12:48 UTC

WeaknessesCWE-61

Technical details

References

Community reviews

Related threats