CVE-2024-20918VulnerabilityPublished 17 Jan 2024Updated 30 Oct 2026

Red Hat Security Advisory: java-21-openjdk security update

Affects Red Hat java-21-openjdkSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2024-20918· High 7.4

Not known to be exploited · CVSS 7.4 High.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

7.4High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (oracle)	CVSS 3.1	7.4

EPSS: 0.9% chance of exploitation in 30 days – higher than 60% 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:H/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
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: 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: 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 16 Jan 2024
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 30 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.
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

AI-suggested

A security update for java-21-openjdk is available from Red Hat for Red Hat Enterprise Linux 9 and related variants. Applying this official update will remediate the identified vulnerabilities. Refer to Red Hat's advisory and update instructions at https://access.redhat.com/articles/11258 for detailed guidance on applying the patch. No additional mitigation steps are indicated beyond applying the update.

Description

Multiple security vulnerabilities have been identified and fixed in the java-21-openjdk packages provided by Red Hat for OpenJDK 21. These include an array out-of-bounds access in the C1 compiler, an RSA padding and timing side-channel issue affecting TLS, a JVM class file verifier flaw allowing unverified bytecode execution, a range check loop optimization problem, and the logging of digital signature private keys. The update addresses these issues in Red Hat Enterprise Linux 9 and related variants.

Impact

The vulnerabilities collectively could lead to memory safety issues (array out-of-bounds), cryptographic weaknesses (RSA padding and timing side-channel attacks), execution of unverified bytecode (potentially bypassing JVM security checks), and exposure of sensitive private keys through logging. These issues pose risks of unauthorized code execution, cryptographic compromise, and leakage of sensitive cryptographic material.

CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-20Improper Input Validation (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #18OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Attack Surface Reduction
Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of…
Architecture and Design · Libraries or Frameworks
Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Server Side Include (SSI) Injection (opens in a new tab)
Cross Zone Scripting (opens in a new tab)
Command Line Execution through SQL Injection (opens in a new tab)
Object Relational Mapping Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-532Insertion of Sensitive Information into Log File (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A09:2025: Security Logging & Alerting Failures (opens in a new tab)
The product writes sensitive information to a log file.
Architecture and Design · Implementation
Consider seriously the sensitivity of the information written into log files. Do not write secrets into the log files.
Distribution
Remove debug log files before deploying the application into production.
Operation
Protect log files against unauthorized read/write.
OWASP Cheat Sheets
Application Logging Vocabulary (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V7.1.1 (opens in a new tab)
V7.1.2 (opens in a new tab)
V8.3.5 (opens in a new tab)
Attack patterns
Fuzzing for application mapping (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-385Covert Timing Channel (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.
Architecture and Design
Whenever possible, specify implementation strategies that do not introduce time variances in operations.
Implementation
Often one can artificially manipulate the time which operations take or -- when operations occur -- can remove information from the attacker.
Implementation
It is reasonable to add artificial or random delays so that the amount of CPU time consumed is independent of the action being taken by the application.
OWASP Cheat Sheets
Cryptographic Storage (opens in a new tab)
Key Management (opens in a new tab)
OWASP ASVS 4.0.3
V6.2.8 (opens in a new tab)
Attack patterns
Cross-Domain Search Timing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 30 Oct 2026, 19:41 UTC

WeaknessesCWE-787, CWE-20, CWE-532 +1

Technical details

References

Community reviews

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