CVE-2025-68475VulnerabilityPublished 22 Dec 2025

CVE-2025-68475: fedify · ReDoS

Affects fedifySource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 1.6.13 soon.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.6.13

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 22 Dec 2025
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 fedify to 1.6.13.

Affected software

Product	Affected	Fixed in
fedify-dev fedify	Affected <1.6.13	Fixed in 1.6.13

AI-suggested

European organizations should immediately audit their use of the Fedify library within federated server applications and identify any deployments running vulnerable versions. The primary mitigation is to upgrade Fedify to the patched versions 1.6.13, 1.7.14, 1.8.15, or 1.9.2 or later, depending on the version branch in use. Where immediate upgrading is not feasible, organizations should implement network-level protections such as rate limiting and input validation to detect and block suspiciously large or malformed HTML responses that could trigger the ReDoS condition. Monitoring CPU usage and application logs for signs of excessive backtracking or performance degradation can provide early warning of exploitation attempts. Developers should review and refactor any custom regular expressions in their ActivityPub implementations to avoid nested quantifiers or other inefficient patterns. Employing Web Application Firewalls (WAFs) with rules targeting ReDoS attack signatures may provide additional defense. Finally, organizations should maintain an incident response plan to quickly address denial of service incidents affecting federated services.

Description

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2, a Regular Expression Denial of Service (ReDoS) vulnerability exists in Fedify's document loader. The HTML parsing regex at packages/fedify/src/runtime/docloader.ts:259 contains nested quantifiers that cause catastrophic backtracking when processing maliciously crafted HTML responses. This issue has been patched in versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2.

Impact

For European organizations, the primary impact of CVE-2025-68475 is the potential for denial of service attacks against federated server applications built with vulnerable versions of Fedify. This can result in service outages, degraded performance, and disruption of federated communication channels, which are increasingly used in decentralized social networking and collaboration platforms. Organizations relying on ActivityPub-based services for internal or external communication, content sharing, or social networking could experience operational interruptions. The impact is particularly significant for entities promoting open, federated platforms such as universities, research institutions, media outlets, and privacy-focused social networks prevalent in Europe. Additionally, denial of service conditions could be leveraged as part of multi-stage attacks or to distract from other malicious activities. Although no confidentiality or integrity impacts are indicated, availability degradation can affect user trust and service reliability. The lack of required authentication or user interaction lowers the barrier for attackers to exploit this vulnerability remotely over the network, increasing risk exposure.

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 22 Dec 2025, 21:56 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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