Red Hat OpenShift Container Platform 4.12: Use of Externally-Controlled Format String
CVE-2026-15809 is a high-severity use of externally-controlled format string vulnerability in Red Hat OpenShift Container Platform 4.12 from Red Hat, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Red Hat OpenShift Container Platform 4.12 you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (redhat.com).
Official description
A flaw was found in CRI-O. The fix for a previous vulnerability (CVE-2022-4318) was incorrect, allowing it to be bypassed. An attacker capable of setting environment variables on a container can inject a newline character into the HOME environment variable. This issue allows the addition of arbitrary lines into /etc/passwd by use of a specially crafted environment variable.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Externally-Controlled Format String
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How developers prevent this class of flaw
- Choose a language that is not subject to this flaw.
- Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
- Run compilers and linkers with high warning levels, since they may detect incorrect usage.
More Use of Externally-Controlled Format String vulnerabilities (CWE-134)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- access.redhat.com/errata/RHSA-2026:57361
- access.redhat.com/errata/RHSA-2026:60444
- access.redhat.com/errata/RHSA-2026:60449
- access.redhat.com/errata/RHSA-2026:60452
- access.redhat.com/errata/RHSA-2026:62548
- access.redhat.com/errata/RHSA-2026:65838
- access.redhat.com/errata/RHSA-2026:65906
- access.redhat.com/errata/RHSA-2026:66385
- access.redhat.com/errata/RHSA-2026:67836
- access.redhat.com/errata/RHSA-2026:67856
- access.redhat.com/errata/RHSA-2026:70585
- access.redhat.com/security/cve/CVE-2026-15809
- bugzilla.redhat.com/show_bug.cgi?id=2500846
Other vulnerabilities in Red Hat OpenShift Container Platform 4.12
- 7.7 High severity
- 7.7 High severity
- 7.5 High severity
- 9.3 Critical severity
- 7.4 High severity
- 7.5 High severity
Recent Use of Externally-Controlled Format String vulnerabilities
- 7.5 High severity
- 8.6 High severity
- 8.1 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
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