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CVE-2026-43974

Unexpected Status Code or Return Value vulnerability in ninenines gun (gun_http module) allows a malicious HTTP server to force the client into raw protocol mode via an unsolicited 101 Switching Protocols response. In gun_http:handle_inform/8, when a 101 Switching Protocols response is received over HTTP/1.1, the function verifies only that the Upgrade header is syntactically valid and that the stream reference is a plain reference(). It does not check whether the client ever sent an Upgrade or
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:c32fc41c9ddd50f32d03a82e79586867698fe9ef6cfa79cb012ef9b280d58e04
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

affected · 2 assertions

{"cpes":["cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["gun_http"],"packageName":"gun","packageURL":"pkg:hex/gun","product":"gun","programFiles":["src/gun_http.erl"],"programRoutines":[{"name":"gun_http:handle_inform/8"}],"repo":"https://github.com/ninenines/gun","vendor":"ninenines","versions":[{"lessThan":"2.4.0","status":"affected","version":"2.0.0","versionType":"semver"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/affected/0

{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["gun_http"],"packageName":"ninenines/gun","packageURL":"pkg:github/ninenines/gun","product":"gun","programFiles":["src/gun_http.erl"],"programRoutines":[{"name":"gun_http:handle_inform/8"}],"repo":"https://github.com/ninenines/gun.git","vendor":"ninenines","versions":[{"lessThan":"5b48068c29ce5e112cb149b5857c7d4dc319a81b","status":"affected","version":"a3c2edbb8c807717e2f10520c6cf1e77a62eab2e","versionType":"git"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/affected/1

Affected products and versions

2 source assertions
{"cpes":["cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["gun_http"],"packageName":"gun","packageURL":"pkg:hex/gun","product":"gun","programFiles":["src/gun_http.erl"],"programRoutines":[{"name":"gun_http:handle_inform/8"}],"repo":"https://github.com/ninenines/gun","vendor":"ninenines","versions":[{"lessThan":"2.4.0","status":"affected","version":"2.0.0","versionType":"semver"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/affected/0
{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["gun_http"],"packageName":"ninenines/gun","packageURL":"pkg:github/ninenines/gun","product":"gun","programFiles":["src/gun_http.erl"],"programRoutines":[{"name":"gun_http:handle_inform/8"}],"repo":"https://github.com/ninenines/gun.git","vendor":"ninenines","versions":[{"lessThan":"5b48068c29ce5e112cb149b5857c7d4dc319a81b","status":"affected","version":"a3c2edbb8c807717e2f10520c6cf1e77a62eab2e","versionType":"git"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/affected/1

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"metric_type":"cvssV4_0"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/metrics/0/cvssV4_0

CWE assertions

1 source assertion
{"cweId":"CWE-841","description":"CWE-841 Improper Enforcement of Behavioral Workflow","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/problemTypes/0/descriptions/0

Source references

3 source assertions
{"tags":["related","third-party-advisory"],"url":"https://cna.erlef.org/cves/CVE-2026-43974.html"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/references/0
{"tags":["patch"],"url":"https://github.com/ninenines/gun/commit/5b48068c29ce5e112cb149b5857c7d4dc319a81b"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/references/2
{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-43974"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:773c56e90a2873c01932143bd4d17e68fa92d2232a380dd8af62fcb64ec4805d · sha256:12cced47cc9d9018… · /containers/cna/references/1

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.

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