CVE Explorer
CVE-2026-26209
cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Versions prior to 5.9.0 are vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding deeply nested CBOR structures. This vulnerability affects both the pure Python implementation and the C extension `_cbor2`. The C extension relies on Python's internal recursion limits `Py_EnterRecursiveCall` rather than a data-driven depth limit, meaning it still ra
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"product":"cbor2","vendor":"agronholm","versions":[{"status":"affected","version":"< 5.9.0"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.0"},"metric_type":"cvssV3_0"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/metrics/0/cvssV3_0
CWE assertions
1 source assertion{"cweId":"CWE-674","description":"CWE-674: Uncontrolled Recursion","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/problemTypes/0/descriptions/0
Source references
4 source assertions{"name":"https://github.com/agronholm/cbor2/commit/e61a5f365ba610d5907a0ae1bc72769bba34294b","tags":["x_refsource_MISC"],"url":"https://github.com/agronholm/cbor2/commit/e61a5f365ba610d5907a0ae1bc72769bba34294b"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/references/2
{"name":"https://github.com/agronholm/cbor2/pull/275","tags":["x_refsource_MISC"],"url":"https://github.com/agronholm/cbor2/pull/275"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/references/1
{"name":"https://github.com/agronholm/cbor2/releases/tag/5.9.0","tags":["x_refsource_MISC"],"url":"https://github.com/agronholm/cbor2/releases/tag/5.9.0"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /containers/cna/references/3
{"name":"https://github.com/agronholm/cbor2/security/advisories/GHSA-3c37-wwvx-h642","tags":["x_refsource_CONFIRM"],"url":"https://github.com/agronholm/cbor2/security/advisories/GHSA-3c37-wwvx-h642"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:ce52d66105a9dbb36f198c94eca3e73843b2f83627d3e798f95c2b93d579a7fb · sha256:fc7c58e8936bf172… · /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.