VulnerabilityPublished 27 Feb 2026

CVE-2026-27707: seerr · Authentication Bypass Using an Alternate Path or Channel

Affects seerrSource CVE Database V5

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Not known to be exploited · CVSS 7.3 High : upgrade to 3.1.0 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

7.3High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.1.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

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: 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: 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 on the impacted component.
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 impacted component 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 impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Feb 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

Upgrade seerr and seerr-team/seerr to 3.1.0.

Affected software

Product	Affected	Fixed in
seerr-teamseerr	Affected >=2.0.0 <3.1.0	Fixed in 3.1.0
GitHubseerr-team/seerr`pkg:github/seerr-team/seerr`Other threats	Affected <3.1.0 >=2.0.0	Fixed in 3.1.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Seerr to version 3.1.0 or later, where this authentication bypass vulnerability is fixed. For environments where immediate upgrade is not feasible, administrators should disable the new Plex login feature (settings.main.newPlexLogin = false) to prevent the vulnerable authentication path. Additionally, explicitly configure the Jellyfin IP setting (settings.jellyfin.ip) to a valid, trusted address rather than leaving it blank to avoid fallback to insecure defaults. Network-level controls should restrict access to the Seerr API endpoints, allowing only trusted clients and servers. Monitoring and logging authentication attempts to detect unusual or unauthorized registrations can help identify exploitation attempts. Finally, review and harden integration points with Radarr and Sonarr to limit the impact of unauthorized requests, including applying least privilege principles and validating incoming requests.

Description

Seerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Starting in version 2.0.0 and prior to version 3.1.0, an authentication guard logic flaw in `POST /api/v1/auth/jellyfin` allows an unauthenticated attacker to register a new Seerr account on any Plex-configured instance by authenticating with an attacker-controlled Jellyfin server. The attacker receives an authenticated session and can immediately use the application with default permissions, including the ability to submit media requests to Radarr/Sonarr. Any Seerr deployment where all three of the following are true may be vulnerable: `settings.main.mediaServerType` is set to `PLEX` (the most common deployment).; `settings.jellyfin.ip` is set to `""` (default, meaning Jellyfin was never configured); and `settings.main.newPlexLogin` is set to `true` (default). Jellyfin-configured and Emby-configured deployments are not affected. Version 3.1.0 of Seerr fixes this issue.

Impact

Organizations running Seerr versions between 2.0.0 and 3.0.x with Plex configured and default Jellyfin settings are at risk of unauthorized access. An attacker can gain authenticated sessions without credentials, potentially leading to unauthorized media requests and manipulation of integrated services like Radarr and Sonarr. This could result in resource misuse, exposure of media request data, and disruption of media management workflows. While the default permissions limit the attacker's capabilities, the breach of authentication undermines system integrity and confidentiality. Additionally, attackers could use this foothold to pivot within the network or escalate privileges if other vulnerabilities exist. Media server environments in home, small business, or community settings relying on Seerr for media management are particularly vulnerable. The vulnerability does not require user interaction and can be exploited remotely, increasing the risk of widespread attacks if unpatched.

CWE-288Authentication Bypass Using an Alternate Path or Channel (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
Architecture and Design
Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V1.2.3 (opens in a new tab)
V1.2.2 (opens in a new tab)
V1.2.4 (opens in a new tab)
Attack patterns
Directory Indexing (opens in a new tab)
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-807Reliance on Untrusted Inputs in a Security Decision (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.
Architecture and Design · Attack Surface Reduction
Store state information and sensitive data on the server side only.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 19:55 UTC

WeaknessesCWE-288, CWE-807

Technical details

References

Community reviews

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