CVE-2026-119283VulnerabilityPublished 30 Oct 2026

joserfc: Unbounded JWE General JSON `recipients` Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key

Affects joserfcSource GCVE Database

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Authoritative record:CVE-2026-119283· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 1.7.5 soon.

Data as of 30 Oct 2026, 18:05 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

Patch: Available – fixed in 1.7.5

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

Attack Vector: Network
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: 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: 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 29 Oct 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 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

Upgrade joserfc to 1.7.5.

Affected software

Product	Affected	Fixed in
PyPIjoserfc	Affected <1.7.5	Fixed in 1.7.5

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

AI-suggested

Upgrade to joserfc version 1.7.5 or later, where this issue is fixed by adding limits on the recipients array. The existing verify_all_recipients=False option does not mitigate CPU exhaustion and should not be relied upon. No other effective mitigations are documented.

Description

The joserfc library's decrypt_json() function for JWE General JSON Serialization accepts an unbounded recipients array, performing an RSA private-key decryption for each recipient without limit. This allows an unauthenticated attacker to cause CPU exhaustion (Denial of Service) by sending a single JWE with many recipients. The library caps other JWE structural elements but does not limit recipient count. The documented mitigation option verify_all_recipients=False does not reduce CPU usage, as all recipients are decrypted regardless. This vulnerability is fixed in joserfc version 1.7.5.

Impact

An unauthenticated attacker can cause a denial of service by sending a JWE General JSON document with a large recipients array to any endpoint using joserfc's decrypt_json() with an RSA key. The victim server performs a costly RSA private-key decryption for each recipient, leading to high CPU usage proportional to the number of recipients. This can degrade or disrupt service availability. No confidentiality or integrity impact is described.

Summary

The joserfc library's public API decrypt_json() parses JWE General JSON Serialization objects and processes the recipients array without any upper bound on its length. For each recipient, the library performs a full RSA private-key decryption operation (decrypt_cek), which is computationally expensive. An attacker can exploit this by crafting a JWE with a large recipients array, causing the victim to perform many RSA decryptions from a single request, leading to CPU exhaustion (CWE-400). The library caps sizes of other JWE components but lacks any check on recipients count. The decrypt loop calls decrypt_recipient() for every recipient before consulting the verify_all_recipients flag, so setting this flag does not mitigate the CPU cost. This vulnerability has a CVSS v3.1 score of 7.5 (High) and is fixed in joserfc 1.7.5.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (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 30 Oct 2026, 18:05 UTC

WeaknessesCWE-400

Technical details

References

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