CVE-2025-55073VulnerabilityPublished 14 Nov 2025Updated 17 Nov 2025

github.com/mattermost/mattermost-server · Mattermost server: Mattermost allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect

Affects github.com/mattermost/mattermost-serverSource GCVE Database

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Authoritative record:CVE-2025-55073· Medium 5.4

Not known to be exploited · CVSS 5.4 Medium : upgrade to 10.11.4 when convenient.

Data as of 13 Nov 2026, 19:31 UTC

CVSS 3.1 base score

5.4Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (Mattermost)	CVSS 3.1	5.4

Patch: Available – fixed in 10.11.4, 10.5.12, 10.12.1 +1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
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: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: 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 14 Nov 2025
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 13 Nov 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
Gogithub.com/mattermost/mattermost-server	Affected >=10.11.0 <10.11.4	Fixed in 10.11.4
Gogithub.com/mattermost/mattermost-server	Affected >=10.5.0 <10.5.12	Fixed in 10.5.12
Gogithub.com/mattermost/mattermost-server	Affected >=10.12.0 <10.12.1	Fixed in 10.12.1
Gogithub.com/mattermost/mattermost/server/v8	Affected <8.0.0-20250929212932-a41db04d2746	Fixed in 8.0.0-20250929212932-a41db04d2746

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 and should be applied by upgrading Mattermost server to versions 10.11.4, 10.5.12, or 10.12.1 or later. Since the vulnerability is fixed in these versions, no additional mitigation steps are required beyond applying the official update.

Description

Mattermost server versions 10.11.x up to 10.11.3, 10.5.x up to 10.5.11, and 10.12.x up to 10.12.0 contain a vulnerability where the MSTeams plugin OAuth flow does not properly validate the relationship to the post being updated. This flaw allows an attacker to edit arbitrary posts by crafting a malicious MSTeams plugin OAuth redirect URL. The issue is fixed in versions 10.11.4, 10.5.12, and 10.12.1.

Impact

An attacker with low privileges can edit arbitrary posts on the Mattermost server by exploiting the improper validation in the MSTeams plugin OAuth redirect flow. This results in integrity loss of post content and a low impact on availability. There is no confidentiality impact reported. The vulnerability does not require user interaction and can be exploited remotely over the network.

Summary

Mattermost server versions >=10.11.0 <10.11.4, >=10.5.0 <10.5.12, and >=10.12.0 <10.12.1 fail to validate the association between a post and the MSTeams plugin OAuth flow. This validation failure enables an attacker to manipulate the OAuth redirect URL to edit arbitrary posts within the Mattermost server. The vulnerability is identified as CWE-306 (Missing Authentication for Critical Function). The CVSS v3.1 score is 5.4 (medium severity) with network attack vector, low attack complexity, requiring low privileges, no user interaction, unchanged scope, no confidentiality impact, limited integrity impact, and low availability impact. Fixed versions are 10.11.4, 10.5.12, and 10.12.1.

CWE-306Missing Authentication for Critical Functionality (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #21OWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
Architecture and Design
Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability.
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…
Architecture and Design
Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment.
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
Choosing Message Identifier (opens in a new tab)
Force the System to Reset Values (opens in a new tab)
Using Unpublished Interfaces or Functionality (opens in a new tab)
Cross Site Request Forgery (opens in a new tab)
Communication Channel Manipulation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Nov 2026, 19:31 UTC

WeaknessesCWE-306

Technical details

References

Community reviews

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