VulnerabilityPublished 29 Oct 2026

CVE-2026-114616: Kimi cli · Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

Affects kimi-cliSource GCVE Database

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Authoritative record:CVE-2026-114616· High 7.4

Not known to be exploited · CVSS 7.4 High.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

7.4High

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	7.4

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 22 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
Homebrewkimi-cli`pkg:brew/kimi-cli`Other threats	Affected >=0.40	Fixed in–

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AI-suggested

Until a fix is available, ensure that the HMAC verification key is never empty at runtime by validating configuration sources such as environment variables or configuration files. Reject or fail startup if the key is empty or missing. Consider using alternative libraries that enforce minimum key length checks.

Description

Authlib versions up to 1.7.2 accept an empty HMAC key for JWS/JWT signature verification using HS256, HS384, and HS512 algorithms. This allows an attacker to forge tokens with arbitrary claims that pass signature verification if the application verifies tokens with an empty key. The vulnerability arises because empty keys produce deterministic, publicly reproducible HMAC digests, and no check rejects zero-length keys in the affected versions.

Impact

Allows attackers to forge arbitrary JWT tokens with valid signatures by exploiting the acceptance of empty HMAC keys, leading to authentication bypass and unauthorized access in systems relying on Authlib for token verification. This can result in elevated privileges or impersonation of other users in OAuth 2.0 and OIDC implementations.

Summary

Authlib's symmetric (oct) key handling does not reject empty keys (empty bytes or empty strings) as valid HMAC signing and verification keys. This flaw exists in Authlib versions up to and including 1.7.2, specifically in the oct_key.py and jws_algs.py modules. The validate_raw_key method only checks for type, allowing empty bytes to pass. The import_key method rejects only keys with unsafe prefixes but not empty keys. The HMACAlgorithm class uses these keys directly in HMAC operations without checking key length. As a result, an empty key produces a deterministic HMAC digest that any party can reproduce, enabling signature forgery. An attacker can exploit this by causing the application to verify tokens with an empty key, for example, if the key is sourced from an environment variable or configuration that defaults to an empty string. This vulnerability is distinct from other recent Authlib JWT advisories and is part of a known family of empty-HMAC-key issues across multiple languages. The flaw allows forging tokens that pass signature verification, leading to authentication bypass in OAuth 2.0 resource servers and OIDC relying parties using Authlib. No live exploitation has been reported, but the vulnerability is confirmed by source code analysis.

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Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 06:31 UTC

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