VulnerabilityPublished 13 Aug 2026Updated 30 Oct 2026

CVE-2026-49854: Snakeviz · Tornado has out-of-bounds memory access via C extension

Affects snakevizSource GCVE Database

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Authoritative record:CVE-2026-49854· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade to 2.2.2_4 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.2.2_4

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 14 Jul 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_4.

Affected software

Product	Affected	Fixed in
Homebrewsnakeviz`pkg:brew/snakeviz`Other threats	Affected >=2.2.0 <2.2.2_4	Fixed in 2.2.2_4

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

AI-suggested

Upgrade to Tornado version 6.5.6 or later, where this vulnerability is fixed. Until the upgrade can be performed, disable the vulnerable native extension by setting the environment variable TORNADO_EXTENSION=0. This disables the 'tornado.speedups' extension, mitigating the vulnerability but may reduce websocket performance.

Description

Tornado's native extension 'tornado.speedups' contains an out-of-bounds memory access vulnerability in the 'websocket_mask' C function. The function reads four bytes from the 'mask' argument without verifying its length, potentially exposing up to three bytes of uninitialized memory. This issue can be triggered via Tornado's XSRF token decoder when 'xsrf_cookies' is enabled and the native extension is active. The vulnerability is fixed in Tornado version 6.5.6. Until upgrading, disabling the native extension via the environment variable TORNADO_EXTENSION=0 mitigates the risk at the cost of reduced websocket performance.

Impact

The vulnerability allows an out-of-bounds memory read of up to three bytes of uninitialized memory, which may lead to information disclosure. The CVSS v3.1 score is 3.7 (Low), reflecting a low-severity confidentiality impact with no integrity or availability impact. Exploitation requires network access with high attack complexity and no privileges or user interaction. There are no known exploits in the wild.

Summary

The vulnerability in Tornado's optional native extension 'tornado.speedups' arises because the 'websocket_mask' C function does not validate that the 'mask' argument is exactly four bytes long. It unconditionally reads four bytes, which can lead to reading beyond the provided buffer if a shorter byte string is passed from Python. This out-of-bounds read can expose up to three bytes of uninitialized memory. The flaw is reachable through Tornado's XSRF token decoder when 'xsrf_cookies' is set to true and the native extension is enabled. The issue is addressed in Tornado 6.5.6. Prior versions from 2.2.0 up to but not including 2.2.2_4 are affected. Mitigation includes disabling the native extension by setting TORNADO_EXTENSION=0 until the upgrade is applied.

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Description

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

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