CVE-2026-59884 (GCVE-0-2026-59884)
Vulnerability from cvelistv5 – Published: 2026-07-14 16:41 – Updated: 2026-07-14 16:41
VLAI
EPSS
VEX
Title
pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
Summary
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
Severity
7.5 (High)
CWE
- CWE-400 - Uncontrolled Resource Consumption
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/pyasn1/pyasn1/security/advisor… | x_refsource_CONFIRM |
| https://github.com/pyasn1/pyasn1/commit/628e36ecb… | x_refsource_MISC |
| https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4 | x_refsource_MISC |
{
"containers": {
"cna": {
"affected": [
{
"product": "pyasn1",
"vendor": "pyasn1",
"versions": [
{
"status": "affected",
"version": "\u003c 0.6.4"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-400",
"description": "CWE-400: Uncontrolled Resource Consumption",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-14T16:41:10.277Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j"
},
{
"name": "https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5"
},
{
"name": "https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4"
}
],
"source": {
"advisory": "GHSA-m4p7-r5rc-7g4j",
"discovery": "UNKNOWN"
},
"title": "pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-59884",
"datePublished": "2026-07-14T16:41:10.277Z",
"dateReserved": "2026-07-07T16:40:07.982Z",
"dateUpdated": "2026-07-14T16:41:10.277Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-59884\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-14T17:17:14.750\",\"lastModified\":\"2026-07-14T17:17:14.750\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"pyasn1\",\"product\":\"pyasn1\",\"versions\":[{\"version\":\"\u003c 0.6.4\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-400\"}]}],\"references\":[{\"url\":\"https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j\",\"source\":\"security-advisories@github.com\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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