VulnerabilityPublished 10 Aug 2026

CVE-2026-19278: Red Hat Advanced Cluster Security 4 · Permissive Regular Expression

Affects Red Hat Advanced Cluster Security 4Source CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium.

Data as of 8 Nov 2026, 23:24 UTC

CVSS 3.1 base score

6.8Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 10 Aug 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 8 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

Affected software

Product	Affected	Fixed in
Red HatRed Hat Advanced Cluster Security 4	Affected–	Fixed in–

AI-suggested

Administrators should review and update all Auth Machine-to-Machine (M2M) role mappings in StackRox/RHACS Central to ensure that the valueExpression regular expressions are properly anchored using start (^) and end ($) delimiters to enforce exact claim value matching. After updating the mappings, reload the configuration or restart the Central service to apply changes.

Description

CVE-2026-19278 is a medium severity vulnerability in Red Hat Advanced Cluster Security 4's StackRox/RHACS Central Auth Machine-to-Machine (M2M) token exchange. The flaw arises from the use of unanchored regular expressions in M2M role mappings, allowing an attacker with a valid OpenID Connect (OIDC) token whose claim value is a superstring of a configured pattern to gain unauthorized roles. This can lead to privilege escalation within the system. No official patch or fix has been explicitly stated yet. Administrators are advised to review and update their M2M role mappings to use properly anchored regular expressions to ensure exact matching and prevent unintended role assignments.

Impact

An attacker with a valid OIDC token can exploit the unanchored regular expressions in M2M role mappings to gain unauthorized access to roles beyond their intended permissions. This leads to privilege escalation within the Red Hat Advanced Cluster Security system, impacting confidentiality and integrity of the system. Availability is not affected. The attack requires an administrator to have configured M2M role mappings with unanchored regex patterns and the attacker to have some level of access to obtain a valid token from a trusted identity provider.

Summary

The vulnerability in StackRox/RHACS Central's Auth M2M token exchange stems from unanchored regular expressions used for matching claim values in role mappings. Because the system performs substring matching rather than exact matching, an attacker possessing a valid OIDC token with a claim value that is a superstring of a configured pattern can escalate privileges by obtaining roles not intended for them. The CVSS v3.1 score is 6.8 (medium severity), reflecting network attack vector, high attack complexity, low privileges required, no user interaction, and high confidentiality and integrity impacts. The vendor advisory recommends anchoring regular expressions (e.g., using ^ and $ delimiters) in the valueExpression to enforce exact matching and prevent unauthorized role assignments. Reloading or restarting the Central service may be necessary for changes to take effect.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Aug 2026, 15:23 UTC

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