VulnerabilityPublished 21 Apr 2026

CVE-2026-40935: WWBN AVideo · Guessable CAPTCHA

Affects WWBN AVideoSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Apr 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

Affected software

Product	Affected	Fixed in
WWBNAVideo	Affected <=29.0	Fixed in–
GitHubwwbn/AVideo`pkg:github/wwbn/AVideo`Other threats	Affected <=29.0	Fixed in–

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AI-suggested

A fix is available in the codebase as identified by commit bf1c76989e6a9054be4f0eb009d68f0f2464b453. Users of WWBN AVideo should apply this fix or upgrade to a version including it. No official vendor advisory or patch release is currently referenced, so users should monitor the vendor's channels for an official update. Until patched, consider implementing additional rate limiting or CAPTCHA validation improvements to mitigate brute-force attempts.

Description

WWBN AVideo versions 29.0 and earlier contain a vulnerability in the CAPTCHA implementation where the CAPTCHA length can be set by an unauthenticated client without validation, allowing generation of a 1-character CAPTCHA. Because the CAPTCHA comparison is case-insensitive over a limited alphabet and failed attempts do not consume the session token, an attacker can brute-force the CAPTCHA in about 33 attempts per session. This affects any endpoint relying on Captcha::validation(), such as user registration and password recovery. A fix is available in commit bf1c76989e6a9054be4f0eb009d68f0f2464b453, but no official vendor advisory or patch release is referenced.

Impact

The vulnerability allows an unauthenticated attacker to bypass CAPTCHA protections by brute-forcing a very short CAPTCHA in a small number of attempts without session token invalidation. This can lead to automated abuse of endpoints protected by CAPTCHA, such as user registration, password recovery, and contact forms, potentially facilitating account enumeration or unauthorized actions. The CVSS score is 5.3 (medium severity), reflecting the ease of exploitation but limited direct confidentiality or availability impact.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Apr 2026, 11:09 UTC

WeaknessesCWE-804

Technical details

References

Community reviews

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