CVE-2026-39834 (GCVE-0-2026-39834)
Vulnerability from cvelistv5
Published
2026-05-22 02:31
Modified
2026-05-22 18:50
Severity ?
VLAI Severity ?
EPSS score ?
Summary
When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| golang.org/x/crypto | golang.org/x/crypto/ssh |
Version: 0 ≤ |
{
"containers": {
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"metrics": [
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"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
"version": "3.1"
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"id": "CVE-2026-39834",
"options": [
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{
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{
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"role": "CISA Coordinator",
"timestamp": "2026-05-22T18:50:30.848292Z",
"version": "2.0.3"
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"providerMetadata": {
"dateUpdated": "2026-05-22T18:50:51.339Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
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"title": "CISA ADP Vulnrichment"
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"cna": {
"affected": [
{
"collectionURL": "https://pkg.go.dev",
"defaultStatus": "unaffected",
"packageName": "golang.org/x/crypto/ssh",
"product": "golang.org/x/crypto/ssh",
"programRoutines": [
{
"name": "channel.WriteExtended"
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{
"name": "Dial"
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{
"name": "Session.CombinedOutput"
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{
"name": "Session.Start"
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{
"name": "channel.Write"
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{
"name": "curve25519sha256.Client"
},
{
"name": "curve25519sha256.Server"
},
{
"name": "dhGEXSHA.Client"
},
{
"name": "dhGEXSHA.Server"
},
{
"name": "dhGroup.Client"
},
{
"name": "dhGroup.Server"
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{
"name": "ecdh.Client"
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{
"name": "ecdh.Server"
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{
"name": "extChannel.Write"
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{
"name": "mlkem768WithCurve25519sha256.Client"
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"vendor": "golang.org/x/crypto",
"versions": [
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"status": "affected",
"version": "0",
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"credits": [
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"lang": "en",
"value": "NCC Group Cryptography Services, sponsored by Teleport"
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"descriptions": [
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"lang": "en",
"value": "When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation."
}
],
"problemTypes": [
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"descriptions": [
{
"description": "CWE-190: Integer Overflow or Wraparound",
"lang": "en"
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"providerMetadata": {
"dateUpdated": "2026-05-22T02:31:27.540Z",
"orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
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"references": [
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"url": "https://go.dev/issue/79567"
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{
"url": "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
},
{
"url": "https://go.dev/cl/781663"
},
{
"url": "https://pkg.go.dev/vuln/GO-2026-5020"
}
],
"title": "Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh"
}
},
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"cveId": "CVE-2026-39834",
"datePublished": "2026-05-22T02:31:27.540Z",
"dateReserved": "2026-04-07T18:13:03.529Z",
"dateUpdated": "2026-05-22T18:50:51.339Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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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.
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