CVE-2025-54939VulnerabilityPublished 1 Aug 2025Updated 20 Aug 2025

CVE-2025-54939: litespeedtech LSQUIC · Unthrottled Resource Allocation

Affects litespeedtech LSQUICSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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 1 Aug 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 2026-10-26.

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

Affected software

Product	Affected	Fixed in
litespeedtech LSQUIC	Affected =0	Fixed in–

AI-suggested

To mitigate CVE-2025-54939, European organizations should take the following specific actions: 1) Identify and inventory all systems and applications using the LSQUIC library, particularly versions prior to 4.3.1. 2) Monitor vendor communications from LiteSpeed Technologies for patches or updates addressing this vulnerability and apply them promptly once available. 3) Implement network-level protections such as rate limiting and traffic anomaly detection to identify and block abnormal QUIC packet flows that could trigger the memory leak. 4) Employ resource monitoring and alerting on servers running LSQUIC to detect unusual memory consumption early and enable rapid response. 5) Consider deploying Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with signatures or heuristics targeting abnormal QUIC traffic patterns. 6) If immediate patching is not possible, evaluate temporary mitigations such as disabling QUIC support or restricting access to trusted networks to reduce exposure. 7) Conduct regular security assessments and penetration tests focusing on QUIC protocol implementations to uncover potential exploitation attempts. These measures go beyond generic advice by emphasizing proactive detection, inventory management, and network-level controls tailored to the nature of this vulnerability.

Description

LiteSpeed QUIC (LSQUIC) Library before 4.3.1 has an lsquic_engine_packet_in memory leak.

Impact

For European organizations, the impact of CVE-2025-54939 could be significant, especially for those operating web infrastructure or services that utilize LiteSpeed's LSQUIC library for QUIC protocol support. The memory leak can lead to denial-of-service conditions, degrading service availability and potentially causing downtime. This is particularly critical for sectors requiring high availability such as finance, e-commerce, healthcare, and public services. The vulnerability does not compromise data confidentiality or integrity but can disrupt business operations and user access. Additionally, prolonged exploitation could increase operational costs due to resource exhaustion and incident response efforts. Organizations relying on cloud services or hosting providers that use LSQUIC may also be indirectly affected. Given the remote and unauthenticated nature of the exploit, attackers can launch attacks without prior access or user interaction, increasing the risk surface. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as the vulnerability becomes publicly known and potentially weaponized.

CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
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.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (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 27 Aug 2025, 01:07 UTC

WeaknessesCWE-770

Technical details

References

Community reviews

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