CVE-2026-103262VulnerabilityPublished 1 Oct 2026Updated 29 Oct 2026

livereload · tornado: CurlAsyncHTTPClient enforces no response-size limit — decompression bomb drives unbounded memory accumulation

Affects livereloadSource GCVE Database

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Authoritative record:CVE-2026-103262· High 8.7

Not known to be exploited · CVSS 8.7 High : upgrade to 2.7.1_4 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

8.7High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.7.1_4

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; 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 Vulnerable System (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).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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 livereload to 2.7.1_4.

Affected software

Product	Affected	Fixed in
Homebrewlivereload`pkg:brew/livereload`Other threats	Affected >=2.7.1 <2.7.1_4	Fixed in 2.7.1_4

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

AI-suggested

A patch is available in livereload version 2.7.1_4 that addresses this vulnerability by introducing response size limits or other mitigations. Users should upgrade to version 2.7.1_4 or later. Until patched, avoid configuring Tornado to use CurlAsyncHTTPClient for fetching untrusted URLs or disable response decompression if possible. No other mitigations are documented.

Description

CVE-2026-103262 is a high-severity vulnerability in Tornado's CurlAsyncHTTPClient where no response size limit is enforced during decompression of HTTP responses. A malicious server can send a compressed payload that expands massively in memory, causing unbounded memory growth and eventual process termination by the operating system's out-of-memory killer. This issue affects Tornado versions from 2.7.1 up to but not including 2.7.1_4. The vulnerability is distinct from a previously fixed decompression bomb issue in Tornado's SimpleAsyncHTTPClient and remains unmitigated in the curl client until patched. A fix is available in version 2.7.1_4.

Impact

An attacker controlling or influencing the HTTP server can cause a Tornado application using CurlAsyncHTTPClient to consume excessive memory by sending a specially crafted compressed response. This leads to unbounded memory accumulation, rapid resource exhaustion, and termination of the Tornado process by the operating system's out-of-memory killer. The vulnerability results in denial of service (DoS) due to application crash or unavailability. There is no impact on confidentiality or integrity reported.

Summary

The vulnerability exists in the Tornado framework's CurlAsyncHTTPClient component, which uses libcurl to fetch HTTP responses. When decompress_response is true (default), libcurl decompresses gzip-encoded responses before passing data to the client callback, which appends decompressed bytes to an unbounded BytesIO buffer without any size checks. This allows a malicious server to send a compressed payload that decompresses to multiple gigabytes, causing the client's memory usage to balloon rapidly until the process is killed by the OS. Unlike the SimpleAsyncHTTPClient, CurlAsyncHTTPClient lacks any max_body_size or similar limits, making it vulnerable to decompression bombs. The issue was verified on Tornado master and release v6.5.8 (corresponding to livereload >=2.7.1 <2.7.1_4). The vulnerability is fixed in livereload version 2.7.1_4. No known exploits are reported in the wild.

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Description

AI analysisMachine-generated, updated 30 Oct 2026, 06:44 UTC

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