CVE-2026-115778VulnerabilityPublished 29 Oct 2026

magic-wormhole · Twisted: Unauthenticated Remote Denial of Service

Affects magic-wormholeSource GCVE Database

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Authoritative record:CVE-2026-115778· High 7.5

Not known to be exploited · CVSS 7.5 High.

Data as of 30 Oct 2026, 07:30 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

CVSS:3.1/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 23 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

Affected software

Product	Affected	Fixed in
Homebrewmagic-wormhole`pkg:brew/magic-wormhole`Other threats	Affected >=0.9.2	Fixed in–

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Description

## Summary An allocation-without-limits vulnerability (CWE-770) in the Twisted conch telnet transport lets any unauthenticated remote peer exhaust server memory over a single connection. When the peer opens a telnet subnegotiation with `IAC SB` and then streams bytes without ever sending the `IAC SE` terminator, every byte is appended to a per-connection buffer that has no maximum length. The buffer persists across reads and is released only on the terminator the attacker withholds, so it grows without bound until the process is killed. ## Details The option-negotiation state machine in `Telnet.dataReceived` enters the `subnegotiation` state on `IAC SB` and sets an empty command list. In that state every non-`IAC` byte is appended to the list with no length check: ```python # src/twisted/conch/telnet.py (Telnet.dataReceived) elif self.state == "subnegotiation": if b == IAC: self.state = "subnegotiation-escaped" else: self.commands.append(b) # unbounded: no len(self.commands) check ``` `self.commands` is an instance attribute that persists across `dataReceived` calls and is deleted only when `IAC SE` completes the subnegotiation. Negotiation runs at the transport layer before authentication, and the bytes are consumed inside `dataReceived` before any application callback, so an application cannot impose a bound. Twisted caps other parser buffers, for example `NetstringReceiver.MAX_LENGTH`, but not this one. Affected product: Twisted, `twisted.conch.telnet` transport Affected versions: confirmed against 26.4.0 ## PoC On any endpoint that exposes the Twisted telnet transport, such as the Twisted manhole telnet service, open one connection and send the two bytes `IAC SB` (`0xFF 0xFA`), then stream any non-`0xFF` bytes continuously and never send the `IAC SE` terminator (`0xFF 0xF0`). No credentials are required, because option negotiation runs before authentication. Every byte is appended to the per-connection subnegotiation buffer with no maximum, and the buffer is released only by the terminator the attacker withholds, so it grows for the life of the connection. Because each byte is retained as a separate element the memory consumed is several times the traffic sent, so a modest-bandwidth peer, or several such connections, drives the process to memory exhaustion. ## Impact This is an unauthenticated remote denial of service (CWE-770, CWE-400) by memory exhaustion. A single connection grows an in-memory buffer without bound at a cost proportional to the bytes sent, amplified by per-byte object overhead, until the operating system kills the server and every service it hosts. There is no confidentiality or integrity impact and no code execution. The affected surface is any deployment that exposes a Twisted telnet or manhole transport to untrusted peers.

References

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