CVE-2026-103262VulnerabilityPublished 1 Oct 2026Updated 30 Oct 2026

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

Affects snakevizSource 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 2.2.2_6 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 2.2.2_6

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 snakeviz to 2.2.2_6.

Affected software

Product	Affected	Fixed in
Homebrewsnakeviz`pkg:brew/snakeviz`Other threats	Affected >=2.2.0 <2.2.2_6	Fixed in 2.2.2_6

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 Tornado version 2.2.2_6 that addresses this vulnerability. Users should upgrade to this fixed version or later to prevent unbounded memory accumulation during response decompression. Until patched, avoid configuring Tornado applications to use CurlAsyncHTTPClient with default decompression enabled on untrusted URLs. 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 gzip-encoded HTTP responses. An attacker-controlled server can send a crafted gzip-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 flaw exists in Tornado versions prior to 2.2.2_6 and is distinct from a related vulnerability fixed in SimpleAsyncHTTPClient. The vulnerability allows denial of service via resource exhaustion when fetching attacker-influenced URLs with default decompression enabled.

Impact

This vulnerability enables a denial-of-service (DoS) attack through unbounded memory consumption. An attacker controlling or compromising an HTTP server can cause any Tornado application using CurlAsyncHTTPClient with default decompression enabled to consume excessive memory rapidly, leading to process termination by the operating system's out-of-memory killer. There is no impact on confidentiality or integrity reported. The attack requires the victim application to fetch attacker-influenced URLs using the vulnerable client configuration.

Summary

The Tornado framework's CurlAsyncHTTPClient component lacks any response size limit when decompressing HTTP responses with gzip encoding. Libcurl automatically decompresses the response before passing data to the client callback, which writes decompressed bytes into an unbounded BytesIO buffer without any size accounting or limits. This allows a malicious HTTP server to send a compressed payload that decompresses to multiple gigabytes, causing the client's memory usage to grow linearly and rapidly until the process is killed by the OS. The vulnerability was verified on Tornado master (6.6.dev1) and release v6.5.8, and affects versions prior to 2.2.2_6. Unlike the SimpleAsyncHTTPClient, which enforces multiple size checks, CurlAsyncHTTPClient has no such protections. The attack chain involves configuring Tornado to use CurlAsyncHTTPClient, fetching a URL controlled by an attacker, and receiving a malicious gzip-compressed response that triggers unbounded memory growth. A patch fixing this issue is available in version 2.2.2_6.

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Description

AI analysisMachine-generated, updated 30 Oct 2026, 06:04 UTC

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