CVE-2026-72887 (GCVE-0-2026-72887)
Vulnerability from cvelistv5
Published
2026-08-16 13:50
Modified
2026-08-17 16:29
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-757 - Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Summary
Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token.
Passing a callback to the constructor selects OAuth 1.0a. get_request_token then revokes that choice when the request token response omits oauth_callback_confirmed, with no exception, no warning and no option to require 1.0a. The access token request is built from the OAuth 1.0 message class, which has no verifier parameter, so oauth_verifier is dropped from the request even when get_access_token was passed one.
oauth_verifier is the binding that OAuth 1.0a added between the authorization step and the token exchange. An application that asked for 1.0a and gets 1.0 is open to OAuth 1.0 session fixation, where an attacker obtains a request token, has the victim authorize it, and then completes the exchange themselves, linking the victim's provider account to a session the attacker controls. No attacker action sets up the downgrade: a provider that does not confirm the callback is enough.
References
| URL | Tags | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||
{
"containers": {
"adp": [
{
"providerMetadata": {
"dateUpdated": "2026-08-16T17:06:04.526Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"url": "http://www.openwall.com/lists/oss-security/2026/08/16/3"
}
],
"title": "CVE Program Container"
},
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2026-72887",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-17T16:29:01.552217Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T16:29:31.019Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://cpan.org/modules",
"defaultStatus": "unaffected",
"modules": [
"Net::OAuth::Client"
],
"packageName": "Net-OAuth",
"packageURL": "pkg:cpan/Net-OAuth",
"programFiles": [
"lib/Net/OAuth/Client.pm"
],
"programRoutines": [
{
"name": "Net::OAuth::Client::get_request_token"
}
],
"repo": "https://github.com/vurtdev/Net-OAuth",
"versions": [
{
"lessThan": "0.32",
"status": "affected",
"version": "0",
"versionType": "custom"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token.\n\nPassing a callback to the constructor selects OAuth 1.0a. get_request_token then revokes that choice when the request token response omits oauth_callback_confirmed, with no exception, no warning and no option to require 1.0a. The access token request is built from the OAuth 1.0 message class, which has no verifier parameter, so oauth_verifier is dropped from the request even when get_access_token was passed one.\n\noauth_verifier is the binding that OAuth 1.0a added between the authorization step and the token exchange. An application that asked for 1.0a and gets 1.0 is open to OAuth 1.0 session fixation, where an attacker obtains a request token, has the victim authorize it, and then completes the exchange themselves, linking the victim\u0027s provider account to a session the attacker controls. No attacker action sets up the downgrade: a provider that does not confirm the callback is enough."
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-757",
"description": "CWE-757 Selection of Less-Secure Algorithm During Negotiation (\u0027Algorithm Downgrade\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-16T13:50:19.052Z",
"orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"shortName": "CPANSec"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://github.com/vurtdev/Net-OAuth/security/advisories/GHSA-jh72-4qq2-8j6g"
},
{
"tags": [
"release-notes"
],
"url": "https://metacpan.org/release/RRWO/Net-OAuth-0.32/changes"
},
{
"tags": [
"patch"
],
"url": "https://github.com/vurtdev/Net-OAuth/commit/fd505dac1988723ed96721657663f2e4ac731644.patch"
},
{
"tags": [
"technical-description"
],
"url": "https://datatracker.ietf.org/doc/html/rfc5849#section-2.1"
},
{
"tags": [
"technical-description"
],
"url": "https://datatracker.ietf.org/doc/html/rfc5849#section-2.3"
}
],
"solutions": [
{
"lang": "en",
"value": "Upgrade to Net-OAuth 0.32 or later."
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token",
"x_generator": {
"engine": "cpansec-cna-tool 0.1"
}
}
},
"cveMetadata": {
"assignerOrgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"assignerShortName": "CPANSec",
"cveId": "CVE-2026-72887",
"datePublished": "2026-08-16T13:50:19.052Z",
"dateReserved": "2026-08-10T15:44:58.172Z",
"dateUpdated": "2026-08-17T16:29:31.019Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"http://www.openwall.com/lists/oss-security/2026/08/16/3\"}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2026-08-16T17:06:04.526Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 9.8, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-72887\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-17T16:29:01.552217Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-17T16:28:44.397Z\"}}], \"cna\": {\"title\": \"Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"affected\": [{\"repo\": \"https://github.com/vurtdev/Net-OAuth\", \"modules\": [\"Net::OAuth::Client\"], \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"0.32\", \"versionType\": \"custom\"}], \"packageURL\": \"pkg:cpan/Net-OAuth\", \"packageName\": \"Net-OAuth\", \"programFiles\": [\"lib/Net/OAuth/Client.pm\"], \"collectionURL\": \"https://cpan.org/modules\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"Net::OAuth::Client::get_request_token\"}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"Upgrade to Net-OAuth 0.32 or later.\"}], \"references\": [{\"url\": \"https://github.com/vurtdev/Net-OAuth/security/advisories/GHSA-jh72-4qq2-8j6g\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://metacpan.org/release/RRWO/Net-OAuth-0.32/changes\", \"tags\": [\"release-notes\"]}, {\"url\": \"https://github.com/vurtdev/Net-OAuth/commit/fd505dac1988723ed96721657663f2e4ac731644.patch\", \"tags\": [\"patch\"]}, {\"url\": \"https://datatracker.ietf.org/doc/html/rfc5849#section-2.1\", \"tags\": [\"technical-description\"]}, {\"url\": \"https://datatracker.ietf.org/doc/html/rfc5849#section-2.3\", \"tags\": [\"technical-description\"]}], \"x_generator\": {\"engine\": \"cpansec-cna-tool 0.1\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token.\\n\\nPassing a callback to the constructor selects OAuth 1.0a. get_request_token then revokes that choice when the request token response omits oauth_callback_confirmed, with no exception, no warning and no option to require 1.0a. The access token request is built from the OAuth 1.0 message class, which has no verifier parameter, so oauth_verifier is dropped from the request even when get_access_token was passed one.\\n\\noauth_verifier is the binding that OAuth 1.0a added between the authorization step and the token exchange. An application that asked for 1.0a and gets 1.0 is open to OAuth 1.0 session fixation, where an attacker obtains a request token, has the victim authorize it, and then completes the exchange themselves, linking the victim\u0027s provider account to a session the attacker controls. No attacker action sets up the downgrade: a provider that does not confirm the callback is enough.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-757\", \"description\": \"CWE-757 Selection of Less-Secure Algorithm During Negotiation (\u0027Algorithm Downgrade\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"9b29abf9-4ab0-4765-b253-1875cd9b441e\", \"shortName\": \"CPANSec\", \"dateUpdated\": \"2026-08-16T13:50:19.052Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-72887\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-17T16:29:31.019Z\", \"dateReserved\": \"2026-08-10T15:44:58.172Z\", \"assignerOrgId\": \"9b29abf9-4ab0-4765-b253-1875cd9b441e\", \"datePublished\": \"2026-08-16T13:50:19.052Z\", \"assignerShortName\": \"CPANSec\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…