VulnerabilityPublished 20 Nov 2025Updated 21 Nov 2025

CVE-2025-62724: OSC ondemand · UNIX Symbolic Link (Symlink) Following

Affects OSC ondemandSource CVE Database V5

Not known to be exploited · CVSS 4.3 Medium : upgrade to 4.0.8 when convenient.

Data as of 26 Oct 2026, 12:29 UTC

CVSS 3.1 base score

4.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.0.8

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

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

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within 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 20 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 osc/ondemand to 4.0.8.

Affected software

Product	Affected	Fixed in
GitHubosc/ondemand`pkg:github/osc/ondemand`Other threats	Affected <4.0.8	Fixed in 4.0.8

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

AI-suggested

Upgrade all Open OnDemand installations to version 4.0.8 or later (or 3.1.16 or later for the 3.x branch) to apply the official patches addressing this vulnerability.
Review and tighten file browser allowlist configurations to ensure minimal necessary directories are accessible, reducing the attack surface.
Implement strict UNIX file permissions and regularly audit file access rights to ensure users cannot read sensitive files outside their scope.
Monitor HPC portal logs for unusual file access patterns or attempts to exploit symlink behavior.
Educate users about the risks of symlink attacks and encourage reporting of suspicious behavior.
Consider deploying additional file integrity monitoring tools to detect unauthorized file access or modifications.
If upgrading immediately is not feasible, restrict user privileges and access to the OOD file browser to trusted users only as a temporary measure.

Description

Open OnDemand is an open-source HPC portal. Prior to versions 4.0.8 and 3.1.16, users can craft a "Time of Check to Time of Use" (TOCTOU) attack when downloading zip files to access files outside of the OOD_ALLOWLIST. This vulnerability impacts sites that use the file browser allowlists in all current versions of OOD. However, files accessed are still protected by the UNIX permissions. Open OnDemand versions 4.0.8 and 3.1.16 have been patched for this vulnerability.

Impact

For European organizations, especially those operating HPC clusters and research facilities using Open OnDemand, this vulnerability could lead to unauthorized disclosure of sensitive data by allowing users to access files outside the intended allowlist. Although UNIX permissions limit file access, the flaw could expose internal configuration files, scripts, or data that should remain restricted, potentially aiding further attacks or data leakage. The impact is primarily on confidentiality, with no direct effect on data integrity or system availability. In research and academic institutions handling proprietary or personal data, this could violate data protection regulations such as GDPR if sensitive personal data is exposed. The medium severity rating reflects the limited scope but non-negligible risk in environments where OOD is deployed. Since HPC portals are often used collaboratively, an insider or compromised user account could exploit this vulnerability to escalate data access beyond intended boundaries. The absence of known exploits reduces immediate risk but does not eliminate the threat, making timely patching critical.

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).
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.3 (opens in a new tab)
V11.1.6 (opens in a new tab)
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/OSC/ondemand/security/advisories/GHSA-vjpg-34px-gjrw (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Nov 2025, 18:23 UTC

WeaknessesCWE-61, CWE-367

Technical details

References

Community reviews

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