VulnerabilityPublished 31 Mar 2023Updated 4 Nov 2025

CVE-2023-28755: uri · ReDoS

Affects uriSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 0.12.1 when convenient.

Data as of 26 Oct 2026, 11:42 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 2.6% chance of exploitation in 30 days – higher than 85% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.12.1

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

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

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: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 31 Mar 2023
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 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 uri to 0.12.1.

Affected software

Product	Affected	Fixed in
RubyGemsuri`pkg:gem/uri`Other threats	Affected <0.12.1	Fixed in 0.12.1
RubyGemsruby`pkg:gem/ruby`Other threats	Affected <=3.2.1	Fixed in–

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-2023-28755, European organizations should prioritize upgrading Ruby to the fixed versions 0.12.1, 0.11.1, 0.10.2, or 0.10.0.1 as appropriate for their environment. Where immediate upgrades are not feasible, implement input validation to reject malformed or suspicious URI inputs before parsing. Employ rate limiting and request throttling on endpoints that accept URI inputs to reduce the risk of resource exhaustion from repeated malicious requests. Monitoring application performance and logs for unusual spikes in URI parsing times can help detect exploitation attempts early. Additionally, consider isolating URI parsing operations in separate processes or containers with resource limits to contain potential denial-of-service impacts. Regularly review and update dependency management practices to ensure timely application of security patches. Finally, conduct security awareness training for developers to recognize and mitigate ReDoS risks in code.

Description

A ReDoS issue was discovered in the URI component through 0.12.0 in Ruby through 3.2.1. The URI parser mishandles invalid URLs that have specific characters. It causes an increase in execution time for parsing strings to URI objects. The fixed versions are 0.12.1, 0.11.1, 0.10.2 and 0.10.0.1.

Impact

For European organizations, the primary impact of CVE-2023-28755 is on service availability. Applications and services that parse URIs using vulnerable Ruby versions may experience significant performance degradation or outages when processing maliciously crafted URLs. This can lead to denial-of-service conditions, affecting business continuity, customer experience, and potentially causing financial losses. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely. However, availability disruptions can impact critical web services, APIs, and backend systems relying on Ruby for URI parsing. Organizations in sectors such as e-commerce, finance, government, and technology that deploy Ruby-based applications are at heightened risk. Additionally, the ease of remote exploitation without authentication increases the threat landscape, especially for publicly accessible services. The absence of known exploits in the wild suggests a window for proactive mitigation before widespread attacks occur.

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

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2025, 01:29 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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