How severe is CVE-2026-26264?

CVE-2026-26264 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2026-26264 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26264?

CVE-2026-26264 primarily affects Bacnetstack Bacnet Stack. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-26264?

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.

Does CVE-2026-26264 have an EU (EUVD) identifier?

Yes. CVE-2026-26264 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6027.

When was CVE-2026-26264 published?

CVE-2026-26264 was published on 2026-02-13 and last updated on 2026-06-17.

CVE-2026-26264

CVE-2026-26264 is a high-severity vulnerability in Bacnetstack Bacnet Stack with a CVSS 3.x base score of 8.1. 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-125.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 7.8
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6027
Weakness: CWE-125
Affected product: Bacnetstack Bacnet Stack
Published: 2026-02-13
Last modified: 2026-06-17

Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size <= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.

Frequently asked questions

What is CVE-2026-26264?: BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size <= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.
How severe is CVE-2026-26264?: CVE-2026-26264 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2026-26264 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26264?: CVE-2026-26264 primarily affects Bacnetstack Bacnet Stack. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-26264?: 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.
Does CVE-2026-26264 have an EU (EUVD) identifier?: Yes. CVE-2026-26264 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6027.
When was CVE-2026-26264 published?: CVE-2026-26264 was published on 2026-02-13 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:bacnetstack:bacnet_stack:*:*:*:*:*:*:*:*
cpe:2.3:a:bacnetstack:bacnet_stack:1.4.3:rc1:*:*:*:*:*:*
cpe:2.3:a:bacnetstack:bacnet_stack:1.5.0:rc1:*:*:*:*:*:*
cpe:2.3:a:bacnetstack:bacnet_stack:1.5.0:rc2:*:*:*:*:*:*
cpe:2.3:a:bacnetstack:bacnet_stack:1.5.0:rc3:*:*:*:*:*:*

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