VulnerabilityPublished 7 Aug 2026

CVE-2026-18938: Red Hat Enterprise Linux 10 · Heap-based Buffer Overflow

Affects Red Hat Enterprise Linux 10Source CVE Database V5

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Not known to be exploited · CVSS 6.2 Medium.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score

6.2Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: 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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 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 5 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 Hat Enterprise Linux 10p11-kit	Affected–	Fixed in–
Red Hat Enterprise Linux 6p11-kit	Affected–	Fixed in–
Red Hat Enterprise Linux 7p11-kit	Affected–	Fixed in–
Red Hat Enterprise Linux 8p11-kit	Affected–	Fixed in–
Red Hat Enterprise Linux 9p11-kit	Affected–	Fixed in–
Red Hat Hardened Imagesp11-kit	Affected–	Fixed in–

AI-suggested

Red Hat currently does not offer a fix or mitigation that meets their criteria for ease of use, deployment, applicability, or stability. Users should monitor the Red Hat advisory for updates.

Description

CVE-2026-18938 is a heap-based buffer overflow vulnerability in the p11-kit component of Red Hat Enterprise Linux 10. It arises from an integer overflow that causes miscalculation of memory allocation for nested attributes, leading to heap out-of-bounds writes. This flaw can be exploited locally or by an attacker with access to a reachable RPC channel to crash the p11-kit RPC parsing process, resulting in a Denial of Service (DoS). The vulnerability is only exploitable on 32-bit systems. No official fix or mitigation currently meets Red Hat's criteria for deployment.

Impact

The primary impact is denial of service due to crashing of the p11-kit RPC parsing process. There is no confidentiality or integrity impact reported. The vulnerability is limited to 32-bit systems and requires local or RPC channel access. No known exploits are reported in the wild. The CVSS v3.1 score is 6.2 (medium severity) reflecting a low complexity local attack causing availability impact only.

Summary

The vulnerability in p11-kit involves an integer overflow during the calculation of attribute-array lengths in RPC messages. This causes under-allocation of memory for nested attributes on 32-bit systems, leading to heap-based buffer overflow and memory corruption. The corrupted memory can crash the p11-kit RPC parsing process, causing a denial of service. The flaw requires local access or equivalent access to an RPC channel. Red Hat has published an advisory but currently does not provide a fix or effective mitigation that meets their standards.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Aug 2026, 16:14 UTC

Technical details

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