How severe is CVE-2023-26436?

CVE-2023-26436 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over physical access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-26436 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-26436?

CVE-2023-26436 primarily affects Open-xchange Open-xchange Appsuite Backend. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-26436?

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

When was CVE-2023-26436 published?

CVE-2023-26436 was published on 2023-06-20 and last updated on 2026-06-17.

CVE-2023-26436

CVE-2023-26436 is a high-severity vulnerability in Open-xchange Open-xchange Appsuite Backend with a CVSS 3.x base score of 7.1. 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-502.

Key facts

Severity: High (CVSS 3.x base score 7.1)
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Open-xchange Open-xchange Appsuite Backend
Published: 2023-06-20
Last modified: 2026-06-17

Description

Attackers with access to the "documentconverterws" API were able to inject serialized Java objects, that were not properly checked during deserialization. Access to this API endpoint is restricted to local networks by default. Arbitrary code could be injected that is being executed when processing the request. A check has been introduced to restrict processing of legal and expected classes for this API. We now log a warning in case there are attempts to inject illegal classes. No publicly available exploits are known.

Frequently asked questions

What is CVE-2023-26436?: Attackers with access to the "documentconverterws" API were able to inject serialized Java objects, that were not properly checked during deserialization. Access to this API endpoint is restricted to local networks by default. Arbitrary code could be injected that is being executed when processing the request. A check has been introduced to restrict processing of legal and expected classes for this API. We now log a warning in case there are attempts to inject illegal classes. No publicly available exploits are known.
How severe is CVE-2023-26436?: CVE-2023-26436 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over physical access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-26436 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-26436?: CVE-2023-26436 primarily affects Open-xchange Open-xchange Appsuite Backend. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-26436?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-26436 published?: CVE-2023-26436 was published on 2023-06-20 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:open-xchange:open-xchange_appsuite_backend:*:*:*:*:*:*:*:*
cpe:2.3:a:open-xchange:open-xchange_appsuite_backend:7.10.6:*:*:*:*:*:*:*
cpe:2.3:a:open-xchange:open-xchange_appsuite_backend:7.10.6:revision_39:*:*:*:*:*:*

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