CVE Explorer
CVE-2026-40279
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, decode_signed32() in src/bacnet/bacint.c reconstructs a 32-bit signed integer from four APDU bytes using signed left shifts. When any of the four bytes has bit 7 set (value ≥ 0x80), the left-shift operation overflows a signed int32_t, which is undefined behavior per the C standard. This is flagged thousands of times per minute by UndefinedBehaviorSanitizer on any BACnet input containing signed-int
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"product":"bacnet-stack","vendor":"bacnet-stack","versions":[{"status":"affected","version":"< 1.4.3"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:6509920051928d6386098b88cb927250b60d35adda8281e726dbccc4530e64b5 · sha256:9de5ba3de04bd531… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},"metric_type":"cvssV3_1"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:6509920051928d6386098b88cb927250b60d35adda8281e726dbccc4530e64b5 · sha256:9de5ba3de04bd531… · /containers/cna/metrics/0/cvssV3_1
CWE assertions
1 source assertion{"cweId":"CWE-758","description":"CWE-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:6509920051928d6386098b88cb927250b60d35adda8281e726dbccc4530e64b5 · sha256:9de5ba3de04bd531… · /containers/cna/problemTypes/0/descriptions/0
Source references
2 source assertions{"tags":["exploit"],"url":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:6509920051928d6386098b88cb927250b60d35adda8281e726dbccc4530e64b5 · sha256:9de5ba3de04bd531… · /containers/adp/0/references/0
{"name":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv","tags":["x_refsource_CONFIRM"],"url":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:6509920051928d6386098b88cb927250b60d35adda8281e726dbccc4530e64b5 · sha256:9de5ba3de04bd531… · /containers/cna/references/0
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.