CVE-2024-0202VulnerabilityPublished 5 Feb 2024Updated 16 Mar 2026

CVE-2024-0202: fedora · Timing Side Channel

Source CVE Database V5

Not known to be exploited · CVSS 5.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.9Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 23% 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 5 Feb 2024
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 2026-10-25.

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 verify whether cryptlib is compiled with RSA key exchange ciphersuites enabled (USE_RSA_SUITES define). If so, they should disable RSA suites in production builds to eliminate exposure to this timing attack. Upgrading to a cryptlib version that does not enable RSA suites by default or applying patches once available is recommended. Network defenders should monitor TLS handshake patterns for unusual connection volumes that could indicate attack attempts. Employing TLS configurations that prefer forward-secure key exchanges such as ECDHE or DHE will mitigate this class of attacks. Additionally, implementing constant-time cryptographic operations and side-channel resistant code paths can reduce timing leakages. Security teams should audit cryptographic libraries and build configurations regularly to ensure deprecated or test-only features are not enabled inadvertently. Finally, organizations should maintain up-to-date threat intelligence to respond promptly if exploit code emerges.

Description

A security vulnerability has been identified in the cryptlib cryptographic library when cryptlib is compiled with the support for RSA key exchange ciphersuites in TLS (by setting the USE_RSA_SUITES define), it will be vulnerable to the timing variant of the Bleichenbacher attack. An attacker that is able to perform a large number of connections to the server will be able to decrypt RSA ciphertexts or forge signatures using server's certificate. THIS CVE ID IS CURRENTLY DISPUTED - MAINTAINER NOTE: There are only two situations where it's enabled, one is for fuzz-testing to exercise code paths that wouldn't otherwise be available, the other is for static source code analysis with tools like Coverity and Prefast, again to open up code paths that otherwise wouldn't be available. It can also be enabled manually in two specific test builds just to make sure the code still compiles OK, to avoid bit rot and verify that the fuzz-testing build will compile without errors.

Impact

If exploited, this vulnerability could allow attackers to decrypt sensitive RSA-encrypted data or forge signatures, undermining the confidentiality and authenticity guarantees of TLS sessions. This could lead to exposure of confidential communications, credential theft, or man-in-the-middle attacks. However, the impact is mitigated by the fact that RSA key exchange ciphersuites are rarely enabled in modern TLS deployments, and cryptlib typically disables them except in test builds. Organizations using cryptlib in legacy or specialized environments that enable RSA suites are at risk. The attack requires the ability to perform numerous TLS handshakes and measure timing precisely, which increases complexity and limits attacker feasibility. There is no known exploitation in the wild, reducing immediate risk. Nevertheless, the vulnerability highlights the dangers of enabling deprecated cryptographic options and the importance of using modern, secure key exchange methods. Failure to address this could result in compromise of server private keys and subsequent widespread security breaches.

Summary

CVE-2024-0202 identifies a timing side-channel vulnerability in the cryptlib cryptographic library version 3.4.7 when compiled with the USE_RSA_SUITES define, which enables RSA key exchange ciphersuites in TLS. This configuration exposes cryptlib to a timing variant of the Bleichenbacher attack, a well-known cryptanalytic attack against RSA PKCS#1 v1.5 padding. An attacker capable of initiating a large number of TLS connections to a vulnerable server can measure subtle timing discrepancies during RSA decryption operations. These timing differences can be exploited to gradually decrypt RSA ciphertexts or forge digital signatures using the server's certificate private key. The vulnerability is notable because it affects cryptlib's implementation of RSA key exchange, which is generally discouraged in favor of more secure key exchange methods like ECDHE. Importantly, the cryptlib maintainer notes that RSA suites are only enabled in specific test builds for fuzz-testing or static analysis purposes, and not in typical production builds. This limits the practical attack surface significantly. The CVSS v3.1 base score is 5.9 (medium severity), reflecting network attack vector, high attack complexity, no privileges or user interaction required, and high confidentiality impact but no integrity or availability impact. No patches or exploits are currently reported, and the vulnerability is disputed due to its limited enabled scenarios. Nevertheless, the presence of this vulnerability in any production environment with RSA suites enabled could lead to serious cryptographic compromise.

References

bugzilla.redhat.com/show_bug.cgi?id=2256518 (opens in a new tab)

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