CVE-2023-26438

CVE-2023-26438 is a medium-severity vulnerability in Open-xchange Open-xchange Appsuite Backend with a CVSS 3.x base score of 4.3. 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-367.

Key facts

Description

External service lookups for a number of protocols were vulnerable to a time-of-check/time-of-use (TOCTOU) weakness, involving the JDK DNS cache. Attackers that were timing DNS cache expiry correctly were able to inject configuration that would bypass existing network deny-lists. Attackers could exploit this weakness to discover the existence of restricted network infrastructure and service availability. Improvements were made to include deny-lists not only during the check of the provided connection data, but also during use. No publicly available exploits are known.

Frequently asked questions

What is CVE-2023-26438?
External service lookups for a number of protocols were vulnerable to a time-of-check/time-of-use (TOCTOU) weakness, involving the JDK DNS cache. Attackers that were timing DNS cache expiry correctly were able to inject configuration that would bypass existing network deny-lists. Attackers could exploit this weakness to discover the existence of restricted network infrastructure and service availability. Improvements were made to include deny-lists not only during the check of the provided connection data, but also during use. No publicly available exploits are known.
How severe is CVE-2023-26438?
CVE-2023-26438 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2023-26438 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-26438?
CVE-2023-26438 primarily affects Open-xchange Open-xchange Appsuite Backend. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-26438?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-26438 published?
CVE-2023-26438 was published on 2023-08-02 and last updated on 2026-06-17.

References

Affected products (2)

More vulnerabilities in Open-xchange Open-xchange Appsuite Backend

All CVEs affecting Open-xchange Open-xchange Appsuite Backend →

Other CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition) vulnerabilities

Browse all CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition) vulnerabilities →