VulnerabilityPublished 30 Oct 2026

CVE-2026-62864: ring · ReDoS

Affects ringSource CVE Database V5

Compare

Not known to be exploited · CVSS 7.5 High : upgrade to 1.15.5 soon.

Data as of 30 Oct 2026, 21:06 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 1.15.5

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 30 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 ring to 1.15.5.

Affected software

Product	Affected	Fixed in
ring-clojurering	Affected <1.15.5	Fixed in 1.15.5

AI-suggested

Upgrade ring to version 1.15.5 or later, where the issue is fixed. Applications using ring middleware nested-params or Ring-Defaults should apply this update to mitigate the vulnerability. If upgrading immediately is not possible, consider disabling the wrap-nested-params middleware if it is not required, as applications omitting this middleware do not expose the vulnerability.

Description

CVE-2026-62864 is a vulnerability in the ring-clojure web application library prior to version 1.15.5. The issue lies in the wrap-nested-params middleware, which uses a backtracking regular expression to parse parameter names from URL query strings and HTTP request bodies. An attacker can craft malicious parameter names that cause quadratic time complexity in regex matching, leading to a denial of service. This affects applications using the middleware, including those using Ring-Defaults where nested-params is enabled by default. The vulnerability is fixed in version 1.15.5.

Impact

The vulnerability allows an unauthenticated remote attacker to cause a denial of service by triggering excessive CPU consumption through crafted parameter names that exploit the inefficient regular expression in the wrap-nested-params middleware. The impact is limited to availability (denial of service) with no confidentiality or integrity impact reported. The CVSS v3.1 score is 7.5 (high severity), reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and impact on availability only.

Summary

Ring, a Clojure web applications library, had a vulnerability (CWE-1333) in the wrap-nested-params middleware prior to version 1.15.5. The middleware uses a backtracking regular expression to match parameter names, which can be exploited by an attacker to cause quadratic O(n^2) regex matching work. This results in a regular-expression denial of service (ReDoS) condition in applications that use this middleware. Ring-Defaults users are also affected since nested-params is enabled by default. Applications that do not use this middleware are not exposed. The issue is resolved in ring version 1.15.5.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
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
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 20:52 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

Related threats