How severe is CVE-2023-40756?

CVE-2023-40756 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-40756 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-40756?

CVE-2023-40756 affects Phpjabbers Callback Widget. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-40756?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2023-40756 published?

CVE-2023-40756 was published on 2023-08-28 and last updated on 2026-06-17.

CVE-2023-40756

CVE-2023-40756 is a critical-severity vulnerability in Phpjabbers Callback Widget with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-203.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-203
Affected product: Phpjabbers Callback Widget
Published: 2023-08-28
Last modified: 2026-06-17

Description

User enumeration is found in PHPJabbers Callback Widget v1.0. This issue occurs during password recovery, where a difference in messages could allow an attacker to determine if the user is valid or not, enabling a brute force attack with valid users.

Frequently asked questions

What is CVE-2023-40756?: User enumeration is found in PHPJabbers Callback Widget v1.0. This issue occurs during password recovery, where a difference in messages could allow an attacker to determine if the user is valid or not, enabling a brute force attack with valid users.
How severe is CVE-2023-40756?: CVE-2023-40756 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-40756 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-40756?: CVE-2023-40756 affects Phpjabbers Callback Widget. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-40756?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2023-40756 published?: CVE-2023-40756 was published on 2023-08-28 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:phpjabbers:callback_widget:1.0:*:*:*:*:*:*:*

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Other CWE-203 (Observable Discrepancy) vulnerabilities

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CVE-2024-25190 — Critical (CVSS 9.8): l8w8jwt 2.2.1 uses memcmp (which is not constant time) to verify authentication, which makes it easier to bypass…

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