CVE-2024-10907VulnerabilityPublished 20 Mar 2025Updated 15 Oct 2025

CVE-2024-10907: lm-sys/fastchat · Loop with Unreachable Exit Condition

Affects lm-sys/fastchatSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.0 base score

7.5High

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.0/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 20 Mar 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

Affected software

Product	Affected	Fixed in
GitHublm-sys/fastchat`pkg:github/lm-sys/fastchat`Other threats	Affected =0.2.36	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Immediate mitigation should focus on implementing input validation and rate limiting at the network or application layer to detect and block malformed multipart requests with excessive boundary characters. Deploying web application firewalls (WAFs) with custom rules to identify and drop suspicious multipart requests can reduce exposure. Organizations should monitor server resource usage closely to detect abnormal spikes indicative of exploitation attempts. If possible, isolate lm-sys/fastchat instances in dedicated environments to contain potential DoS impacts. Until an official patch is released, consider disabling or restricting multipart request handling if feasible. Engage with the vendor or open-source maintainers to obtain updates or patches addressing this issue. Regularly update intrusion detection systems (IDS) signatures to include detection for this vulnerability. Finally, develop incident response plans specifically for DoS scenarios targeting this vulnerability to minimize downtime.

Description

In lm-sys/fastchat Release v0.2.36, the server fails to handle excessive characters appended to the end of multipart boundaries. This flaw can be exploited by sending malformed multipart requests with arbitrary characters at the end of the boundary. Each extra character is processed in an infinite loop, leading to excessive resource consumption and a complete denial of service (DoS) for all users. The vulnerability is unauthenticated, meaning no user login or interaction is required for an attacker to exploit this issue.

Impact

For European organizations deploying lm-sys/fastchat, this vulnerability could lead to significant service outages due to denial of service attacks. Critical services relying on fastchat for communication or AI-driven interactions may become unavailable, impacting business continuity and user experience. The unauthenticated nature of the exploit means attackers can launch DoS attacks without needing credentials or insider access, increasing the attack surface. Organizations in sectors such as finance, healthcare, and government that depend on real-time chat or AI services could face operational disruptions and potential reputational damage. Additionally, resource exhaustion might indirectly affect other hosted services on the same infrastructure, amplifying the impact. Given the lack of known exploits, the threat is currently theoretical but could escalate rapidly once exploit code becomes available. European data centers hosting these services might experience increased load and potential cascading failures if targeted at scale.

References

huntr.com/bounties/bf3ca81d-3508-4455-95d9-0b653e46d6e4 (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 15 Oct 2025, 13:19 UTC

WeaknessesCWE-835

Technical details

References

Community reviews

Related threats