CVE-2025-8546VulnerabilityPublished 5 Aug 2025

CVE-2025-8546: atjiu pybbs · Guessable CAPTCHA

Affects atjiu pybbsSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system 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 Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within 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: 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
atjiu pybbs	Affected =6.0	Fixed in–

AI-suggested

To mitigate this vulnerability, European organizations should immediately identify all instances of atjiu pybbs version 6.0.0 or earlier in their environment and apply the official patch referenced by commit ecaf8d46944fd03e3c4ea05698f8acf0aaa570cf. Beyond patching, organizations should consider implementing additional security controls such as rate limiting and IP blacklisting on the admin login endpoint to reduce the effectiveness of automated brute-force attacks. Enabling multi-factor authentication (MFA) for administrative accounts will add a critical layer of defense even if CAPTCHA is bypassed. Monitoring login attempts and setting up alerts for suspicious activity can help detect exploitation attempts early. If patching is delayed, temporarily disabling remote administrative login or restricting access to trusted IP ranges can reduce exposure. Finally, reviewing and enforcing strong password policies for administrative users will mitigate the risk of credential compromise.

Description

A vulnerability, which was classified as problematic, was found in atjiu pybbs up to 6.0.0. This affects the function adminlogin/login of the component Verification Code Handler. The manipulation leads to guessable captcha. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The patch is named ecaf8d46944fd03e3c4ea05698f8acf0aaa570cf. It is recommended to apply a patch to fix this issue.

Impact

For European organizations using atjiu pybbs version 6.0.0 or earlier, this vulnerability poses a risk of unauthorized administrative access due to the guessable CAPTCHA. Successful exploitation could allow attackers to bypass the CAPTCHA protection and launch automated login attempts without restriction, increasing the likelihood of credential compromise or account takeover. This could lead to unauthorized administrative control over the forum or bulletin board system, enabling attackers to manipulate content, exfiltrate sensitive information, or use the compromised system as a foothold for further network intrusion. Given that pybbs is a forum software, organizations relying on it for internal or public communications could face reputational damage, data leakage, or disruption of services. The medium severity rating reflects that while the vulnerability alone does not grant direct access, it significantly lowers the barrier for brute-force attacks. European organizations in sectors with high reliance on online community platforms, such as education, government, or public services, may be particularly impacted if they have not applied the patch. Additionally, the remote exploitability and lack of required user interaction increase the threat surface.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Aug 2025, 05:32 UTC

Technical details

References

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