CVE-2026-103001VulnerabilityPublished 1 Oct 2026Updated 27 Oct 2026

Hermes agent: PyJWT.decode() reintroduces options-dict mutation, enabling silent claim-verification bypass on dict

Affects hermes-agentSource GCVE Database

Authoritative record:CVE-2026-103001· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 0.22.4 when convenient.

Data as of 27 Oct 2026, 21:00 UTC

CVSS 3.1 base score

6.5Medium

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

Patch: Available – fixed in 0.22.4

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
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: 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: 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 30 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 hermes-agent to 0.22.4.

Affected software

Product	Affected	Fixed in
Homebrewhermes-agent`pkg:brew/hermes-agent`Other threats	Affected >=0.21.6 <0.22.4 >=2026.4.30 <=2026.9.24	Fixed in 0.22.4

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 PyJWT version 0.22.4 that restores a shallow copy of the options dictionary inside the _merge_options() function to prevent mutation of caller-supplied dictionaries. Users should upgrade to version 0.22.4 or later to remediate this issue. Until patched, avoid reusing the same options dictionary across decode calls with different verification settings; instead, create a fresh options dictionary for each call.

Description

PyJWT versions from 0.21.6 up to but not including 0.22.4, and versions from 2026.4.30 through 2026.9.24, contain a vulnerability where the decode() function mutates a caller-supplied options dictionary when signature verification is disabled. If the same options dictionary is reused with signature verification enabled later, it can silently bypass claim verifications such as expiration, audience, issuer, and subject checks. This leads to acceptance of expired or otherwise invalid tokens without exceptions. The issue is a regression introduced in March 2025 and fixed in version 0.22.4. The vulnerability has a medium severity with a CVSS score of 6.5.

Impact

This vulnerability allows an attacker to bypass claim verification checks such as expiration, audience, issuer, subject, and others if the application reuses the same mutable options dictionary across multiple decode calls with different verification intents. This results in acceptance of tokens that should be rejected due to invalid claims, potentially leading to unauthorized access or privilege escalation. Signature verification itself is not bypassed. The impact is limited to applications that reuse the options dictionary and do not create a fresh one per decode call.

Summary

The PyJWT library's decode() and decode_complete() functions mutate the caller-supplied options dictionary in place when verify_signature is set to false, adding keys that disable claim verification (e.g., verify_exp, verify_nbf). If an application reuses the same options dictionary across calls, a subsequent call with verify_signature set to true inherits these disabled claim checks, allowing expired or invalid tokens to be accepted without exception. This is a regression of a previously fixed issue, reintroduced by a code refactor in March 2025 that removed a shallow copy of the options dictionary. The vulnerability affects all PyJWT releases from the merge of PR #1045 (2025-03-05) through 2.13.0, including the affected hermes-agent versions. The fix involves restoring a shallow copy of the options dictionary before mutation to prevent caller-side mutation.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Oct 2026, 21:00 UTC

Technical details

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