CVE-2023-5981VulnerabilityPublished 28 Nov 2023Updated 6 Nov 2025

CVE-2023-5981: Red Hat Enterprise Linux 8 · Observable Discrepancy

Affects Red Hat Enterprise Linux 8Source CVE Database V5

Not known to be exploited · CVSS 5.9 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.9Medium

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

EPSS: 1.2% chance of exploitation in 30 days – higher than 69% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
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: 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: 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: 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: 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 28 Nov 2023
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 2026-10-26.

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 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

AI-suggested

Organizations should monitor Red Hat advisories closely and apply security patches promptly once they become available to address CVE-2023-5981. In the interim, administrators should consider disabling RSA-PSK cipher suites or migrating to more secure key exchange mechanisms such as ECDHE or DHE that are not vulnerable to this timing side-channel. Network-level mitigations include implementing strict rate limiting and anomaly detection on TLS handshake traffic to hinder timing analysis attacks. Employing hardware security modules (HSMs) or cryptographic accelerators that perform constant-time operations can reduce timing leakages. Additionally, organizations should conduct internal security assessments and penetration tests focusing on TLS implementations to detect potential side-channel vulnerabilities. Ensuring comprehensive logging and monitoring of TLS handshake anomalies can aid in early detection of exploitation attempts. Finally, educating security teams about timing side-channel risks and mitigation strategies will enhance overall defensive posture.

Description

A vulnerability was found that the response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from response times of ciphertexts with correct PKCS#1 v1.5 padding.

Impact

For European organizations, especially those in sectors such as finance, government, telecommunications, and critical infrastructure, this vulnerability could lead to the compromise of confidential communications and cryptographic keys if exploited. Given Red Hat Enterprise Linux 8's prevalence in enterprise servers and cloud platforms, attackers could leverage this timing side-channel to extract sensitive information remotely, potentially undermining data confidentiality and trust in secure communications. Although the vulnerability does not affect system integrity or availability, the exposure of cryptographic secrets could facilitate further attacks, including unauthorized data decryption or impersonation. The medium severity rating reflects the balance between the difficulty of exploitation and the potential confidentiality impact. Organizations relying on RSA-PSK cipher suites in TLS configurations are particularly at risk. The lack of known exploits in the wild reduces immediate urgency but does not eliminate future risk, especially as attackers develop more sophisticated timing analysis techniques.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 11 Nov 2025, 20:01 UTC

Technical details

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