CVE-2025-55127VulnerabilityPublished 20 Nov 2025

CVE-2025-55127: Revive Adserver · Vulnerability

Affects Revive AdserverSource CVE Database V5

Not known to be exploited · CVSS 5.4 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.4Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
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: 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: 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: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Nov 2025
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 2026-10-25.

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 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
Revive Revive Adserver	Affected =6	Fixed in–

AI-suggested

To mitigate CVE-2025-55127, organizations should implement the following specific measures: 1) Enforce strict username normalization by trimming leading and trailing whitespace characters during user creation and updates to prevent visually deceptive usernames. 2) Enhance the user interface to visually indicate or highlight whitespace characters in usernames, reducing the chance of confusion. 3) Restrict user creation privileges to trusted administrators only, minimizing the risk of attacker-controlled accounts. 4) Implement monitoring and alerting for suspicious username patterns or duplicate-looking usernames. 5) Conduct regular audits of user accounts to identify and remediate any accounts with suspicious whitespace usage. 6) Engage with the Revive Adserver vendor community to obtain patches or updates addressing this vulnerability once available. 7) Educate administrators and users about the risk of username impersonation and encourage vigilance in verifying user identities. 8) Consider deploying multi-factor authentication and role-based access controls to limit the impact of compromised or impersonated accounts. These targeted actions go beyond generic advice by focusing on the unique nature of whitespace-based impersonation and user management controls.

Description

HackerOne community member Dao Hoang Anh (yoyomiski) has reported an improper neutralization of whitespace in the username when adding new users. A username with leading or trailing whitespace could be virtually indistinguishable from its legitimate counterpart when the username is displayed in the UI, potentially leading to confusion.

Impact

For European organizations, this vulnerability poses a moderate risk primarily to the integrity and confidentiality of user identity within the Revive Adserver platform. Attackers exploiting this flaw could create accounts that appear identical to legitimate users, potentially enabling unauthorized actions under the guise of trusted users or causing administrative confusion. This could lead to misattribution of actions, unauthorized access to advertising campaign management, or manipulation of ad delivery settings. While it does not directly compromise system availability or allow remote code execution, the impersonation risk can undermine trust in the platform and complicate incident response. Organizations heavily reliant on Revive Adserver for digital advertising campaigns may face operational disruptions or reputational damage if attackers exploit this vulnerability. Given the network attack vector and low privilege requirement, insider threats or compromised accounts could be leveraged to exploit this issue. The absence of known exploits reduces immediate risk but does not eliminate the need for proactive mitigation.

CWE-156Improper Neutralization of Whitespace (opens in a new tab)
Variant weakness
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as whitespace when they are sent to a downstream component.
Developers should anticipate that whitespace will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Output Encoding
While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
V5.2.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

hackerone.com/reports/3413764 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Nov 2025, 20:22 UTC

WeaknessesCWE-156

Technical details

References

Community reviews

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