VulnerabilityPublished 7 Feb 2026Updated 23 Feb 2026

CVE-2026-2109: jsbroks COCO Annotator · Improper Authorization

Affects jsbroks COCO AnnotatorSource CVE Database V5

Public exploit available · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 4.0 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 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, 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

Affected software

Product	Affected	Fixed in
jsbroksCOCO Annotator	Affected =0.11.0 =0.11.1	Fixed in–

CPE configurations (1)

cpe:2.3:a:jsbroks:coco_annotator:*:*:*:*:*:*:*:*

AI-suggested

Immediately restrict access to the /api/undo/ endpoint by implementing network-level controls such as IP whitelisting or VPN-only access to the COCO Annotator service.
Enforce strict authentication and authorization mechanisms around all API endpoints, especially those that modify or delete data.
Implement application-layer access controls to validate user permissions before processing deletion or undo requests.
Monitor logs and network traffic for unusual or unauthorized API calls targeting the /api/undo/ endpoint.
Isolate COCO Annotator instances from public internet exposure where possible.
Regularly back up annotation datasets to enable recovery in case of data tampering or deletion.
Engage with the vendor or community for updates and patches; consider contributing fixes if feasible.
Consider deploying web application firewalls (WAFs) with custom rules to detect and block suspicious manipulation of the ID parameter.
Educate users and administrators about the vulnerability and encourage vigilance for anomalous behavior.
Plan for rapid patch deployment once an official fix becomes available.

Description

A vulnerability was identified in jsbroks COCO Annotator up to 0.11.1. Affected is an unknown function of the file /api/undo/ of the component Delete Category Handler. Such manipulation of the argument ID leads to improper authorization. The attack may be launched remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

The vulnerability could lead to unauthorized deletion or modification of annotation categories within COCO Annotator, compromising the integrity of labeled datasets. This can disrupt machine learning workflows, degrade model quality, and cause operational delays. Organizations relying on COCO Annotator for critical AI/ML projects may face data loss or corruption, impacting research, product development, or AI-driven services. The availability of annotation data could also be affected if attackers delete essential categories, causing denial of service conditions for annotation teams. Since the vulnerability is remotely exploitable without authentication, attackers can launch attacks from anywhere, increasing the threat surface. The lack of vendor response and absence of patches prolong exposure, raising the risk of exploitation especially in environments where COCO Annotator is internet-facing or insufficiently access-controlled. Overall, the impact is moderate but significant for organizations dependent on accurate and reliable annotation data.

References

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