VulnerabilityPublished 31 Oct 2026

CVE-2026-119196: Kimi cli · pyasn1 has quadratic CPU consumption in constructed BIT STRING decoding

Affects kimi-cliSource GCVE Database

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Authoritative record:CVE-2026-119196· High 7.5

Not known to be exploited · CVSS 7.5 High.

Data as of 31 Oct 2026, 15:55 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 29 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 30 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
Homebrewkimi-cli`pkg:brew/kimi-cli`Other threats	Affected >=0.56	Fixed in–

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AI-suggested

Until a fix is available, applications should consider limiting or validating ASN.1 input sizes and fragment counts before decoding to mitigate potential CPU exhaustion. Avoid decoding untrusted ASN.1 data that may contain constructed BIT STRINGs with many fragments. Monitor vendor communications for updates and patches.

Description

CVE-2026-119196 affects pyasn1 through version 0.6.4, where decoding constructed BIT STRING values with many fragments causes quadratic CPU consumption due to repeated shifting and copying of accumulated data. This can lead to CPU exhaustion and denial of service if attacker-controlled ASN.1 data with many fragments is decoded. The vulnerability impacts BER and CER decoders, and a permissive schema-driven DER decoder path. No confidentiality or integrity impact is reported. The CVSS v3.1 base score is 7.5 (high severity).

Impact

An attacker can cause denial of service by supplying crafted ASN.1 data containing many constructed BIT STRING fragments to an application using the affected pyasn1 decoder paths. The CPU consumption grows quadratically with the number of fragments, potentially exhausting CPU resources during decoding. There is no impact on confidentiality or integrity. The vulnerability requires that untrusted input reaches the vulnerable decoder path and that input limits allow sufficiently many fragments. The severity is high with a CVSS score of 7.5.

Summary

In pyasn1 versions up to 0.6.4, the BitStringPayloadDecoder processes constructed BIT STRING values by repeatedly shifting and copying the entire accumulated value for each fragment. This results in CPU time growing quadratically with the number of fragments. The BER and CER decoders reach this vulnerable code path for constructed BIT STRING values, while the DER decoder's schema-driven path also permits definite-length constructed BIT STRING decoding, triggering the same issue. The vulnerability arises because the decoder shifts an ever-larger Python integer for each fixed-size fragment, causing excessive CPU usage. This can be exploited by passing large, attacker-controlled ASN.1 data to the decoder, potentially causing denial of service by exhausting CPU resources during decoding. The vulnerability does not affect confidentiality or integrity. The advisory clarifies that not all applications using pyasn1 are necessarily exposed, depending on input acceptance and limits.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 31 Oct 2026, 15:55 UTC

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