MediumCVE-2026-107833

OWASP Coraza WAF: Unbounded recursion in JSON response body processor causes CPU exhaustion (CVE-2026-107833)

Published 09.10.2026Last modified 09.10.2026Sources: CVE.org, OSV

Public exploit

What is affected, what to do

An exploit is publicly available. Update github.com/corazawaf/coraza/v3 to version 3.8.0.

Affected: Coraza gte 3.0.0, < 3.8.0..*

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

5.9

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: Vendor (CNA), CVSS v3

5.9

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: CVE.org, OSV

0.4 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 32.7

Show all metrics

Severity: Medium
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 68.08 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: PoC (publicly reported)
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 5.9 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 5.9
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.4 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 32.7; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 09.10.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-674

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. From 3.0.0 until 3.8.0, ProcessResponse in internal/bodyprocessors/json.go passes the ignoreJSONRecursionLimit value of -1 to readJSON, while the recursive guard only stops at zero. A network attacker who can cause an application protected by Coraza to return deeply nested JSON can make response-body processing perform quadratic work, consuming one CPU core for seconds per response within the default ResponseBodyLimit. Request JSON processing is not affected by this specific path because it uses the configured request recursion limit, and exploitation requires response-body inspection to be enabled. This issue is fixed in version 3.8.0.

Source: NVD (NIST), cvelistv5, OSV (Open Source Vulnerabilities)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
corazawaf	coraza	`≥ 3.0.0, < 3.8.0`	—
go	github.com/corazawaf/coraza	`—`	—
go	github.com/corazawaf/coraza/v2	`—`	—
go	github.com/corazawaf/coraza/v3	`3.0.0`	`3.8.0`

Vendors and products

Weakness classes (CWE)

CWE-674Uncontrolled Recursion
Class
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Entry at MITRE CWE-674

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

CIRCL Sightings	github.com (opens in a new tab)	PoC (publicly reported)reported, not verified	02.10.2026

References & sources

github.comcorazawaf/coraza/security/advisories/GHSA-3c6w-j9xm-8h2hweb, x_refsource_CONFIRM, advisory
github.comcorazawaf/coraza/commit/cae3c7407e7b84372c207033de03f15f89bf351aweb, x_refsource_MISC, fix
github.comcorazawaf/corazapackage
github.comcorazawaf/coraza/releases/tag/v3.8.0web, x_refsource_MISC

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

09.10.2026ReceivedGitHub

CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type: CWE-674

Description added or changed

New references:

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. From 3.0.0 until 3.8.0, ProcessResponse in internal/bodyprocessors/json.go passes the ignoreJSONRecursionLimit value of -1 to readJSON, while the recursive guard only stops at zero. A network attacker who can cause an application protected by Coraza to return deeply nested JSON can make response-body processing perform quadratic work, consuming one CPU core for seconds per response within the default ResponseBodyLimit. Request JSON processing is not affected by this specific path because it uses the configured request recursion limit, and exploitation requires response-body inspection to be enabled. This issue is fixed in version 3.8.0.
CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness type (CWE)	added	—	CWE-674
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/107xxx/CVE-2026-107833.json">CVE-2026-107833</a>
Reference	added	—	https://github.com/corazawaf/coraza/commit/cae3c7407e7b84372c207033de03f15f89bf351a
Reference	added	—	https://github.com/corazawaf/coraza/releases/tag/v3.8.0
Reference	added	—	https://github.com/corazawaf/coraza/security/advisories/GHSA-3c6w-j9xm-8h2h

Source identifier: security-advisories@github.com

09.10.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: proof of concept, automatable: no

New references:

https://github.com/corazawaf/coraza/security/advisories/GHSA-3c6w-j9xm-8h2h

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/corazawaf/coraza/security/advisories/GHSA-3c6w-j9xm-8h2h
SSVC assessment	added	—	{"id":"CVE-2026-107833","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-09T18:01:32.504807Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

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