VulnerabilityPublished 25 Feb 2026

CVE-2024-27454: orjson · Uncontrolled Recursion

Affects orjsonSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 3.9.15 soon.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 1.1% chance of exploitation in 30 days – higher than 67% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.9.15

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

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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).
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).
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted 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.
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.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Feb 2026
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 26 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.
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

Upgrade orjson to 3.9.15.

Affected software

Product	Affected	Fixed in
PyPIorjson`pkg:pypi/orjson`Other threats	Affected <3.9.15	Fixed in 3.9.15

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2024-27454, organizations should immediately upgrade orjson to version 3.9.15 or later, where recursion limits have been implemented to prevent this vulnerability. If upgrading is not immediately feasible, implement input validation and sanitization to detect and reject JSON documents with excessive nesting depth before deserialization. Employ runtime monitoring and resource limits (such as CPU and memory quotas) on services processing JSON to detect and contain abnormal resource consumption. Consider using alternative JSON libraries with built-in recursion protections if orjson cannot be updated promptly. Additionally, apply network-level protections such as web application firewalls (WAFs) to block suspicious payloads and rate-limit requests to reduce exposure to denial of service attempts. Regularly audit dependencies and maintain an inventory of libraries to ensure timely patching of known vulnerabilities. Finally, incorporate fuzz testing and security testing focused on JSON parsing to proactively identify similar issues in development.

Description

orjson.loads in orjson before 3.9.15 does not limit recursion for deeply nested JSON documents.

Impact

The primary impact of CVE-2024-27454 is denial of service, where an attacker can cause applications using vulnerable orjson versions to crash or hang by sending deeply nested JSON payloads. This can disrupt availability of critical services, leading to downtime, degraded user experience, and potential cascading failures in dependent systems. Since orjson is widely used in Python environments for performance-critical JSON processing, many web applications, APIs, and backend services are at risk. The vulnerability does not affect confidentiality or integrity directly but can be leveraged as part of a broader attack chain to cause service interruptions. Organizations relying on orjson in exposed environments face increased risk of service outages, impacting business continuity and potentially leading to financial and reputational damage. The ease of exploitation and lack of required privileges or user interaction make this a significant threat, especially in cloud-native and microservice architectures where JSON parsing is frequent and often exposed to external inputs.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Feb 2026, 22:27 UTC

WeaknessesCWE-674

Technical details

References

Community reviews

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