VulnerabilityPublished 5 Aug 2025

CVE-2025-8551: atjiu pybbs · Cross-site Scripting

Affects atjiu pybbsSource CVE Database V5

Public exploit available · CVSS 5.1 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score

5.1Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% 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:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: Passive
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: None
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: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
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: None: There is no impact to availability within 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 5 Aug 2025
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
atjiu pybbs	Affected =6.0	Fixed in–

AI-suggested

To mitigate this vulnerability, European organizations should promptly apply the official patch identified by commit 2fe4a51afbce0068c291bc1818bbc8f7f3b01a22 to all affected pybbs installations. In parallel, organizations should implement strict input validation and output encoding on all user-supplied data, particularly in administrative interfaces. Employing Content Security Policy (CSP) headers can reduce the impact of potential XSS attacks by restricting script execution sources. Monitoring and logging administrative access and unusual activities in the /admin/comment/list area can help detect exploitation attempts early. If immediate patching is not feasible, restricting access to the administrative interface via IP whitelisting or VPNs can reduce exposure. Regular security awareness training for administrators to recognize suspicious content or behavior is also recommended. Finally, organizations should review their pybbs deployment to ensure it follows security best practices, including running the latest supported versions and minimizing unnecessary privileges.

Description

A vulnerability was found in atjiu pybbs up to 6.0.0. It has been rated as problematic. Affected by this issue is some unknown functionality of the file /admin/comment/list. The manipulation of the argument Username leads to cross site scripting. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The name of the patch is 2fe4a51afbce0068c291bc1818bbc8f7f3b01a22. It is recommended to apply a patch to fix this issue.

Impact

For European organizations using atjiu pybbs, especially those deploying it for internal or external community forums, this vulnerability poses a risk to administrative account security. Successful exploitation could lead to session hijacking, unauthorized administrative actions, or injection of malicious content, potentially compromising sensitive information or damaging organizational reputation. Given the administrative context of the vulnerability, attackers could manipulate forum content or user data, impacting data integrity and trustworthiness. The medium severity rating indicates a moderate risk; however, the lack of authentication requirement and remote exploitability increase the urgency of patching. Organizations in sectors with strict data protection regulations (e.g., GDPR) could face compliance issues if such an attack leads to data breaches. Additionally, public-facing forums used by European companies could be leveraged as attack vectors for broader social engineering or phishing campaigns targeting employees or customers.

Summary

CVE-2025-8551 is a cross-site scripting (XSS) vulnerability identified in the atjiu pybbs software, specifically affecting versions up to 6.0.0. The vulnerability exists in the /admin/comment/list functionality where the 'Username' argument is improperly sanitized, allowing an attacker to inject malicious scripts. This flaw can be exploited remotely without requiring authentication, although user interaction is necessary for the attack to succeed (e.g., an administrator viewing a crafted comment list). The vulnerability has been publicly disclosed, and a patch identified by commit 2fe4a51afbce0068c291bc1818bbc8f7f3b01a22 is available to remediate the issue. The CVSS 4.0 base score is 5.1 (medium severity), reflecting the network attack vector, low attack complexity, no privileges required, but requiring user interaction. The impact primarily affects the confidentiality and integrity of administrative sessions, as malicious scripts could steal session tokens, perform actions on behalf of the admin, or deface the administrative interface. The vulnerability does not affect availability and does not require prior authentication, increasing its risk profile. Although no known exploits are currently active in the wild, the public disclosure raises the likelihood of exploitation attempts. The vulnerability is limited to the pybbs product, a Python-based bulletin board system, which is typically used by organizations for community forums or internal communications.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Aug 2025, 08:02 UTC

Technical details

References

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