Golang go.crypto: When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in
Affects golang-go.cryptoSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical · fixed in 1:0.0~git20151201.0.7b85b09-2ubuntu0.1~esm2 : patch golang-go.crypto as a priority.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1:0.0~git20151201.0.7b85b09-2ubuntu0.1~esm2, 2.0.11-0ubuntu1~16.04.4+esm3, 20240716.00-0ubuntu1~16.04.0+esm3 +12
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10snapdpkg:deb/ubuntu/snapd?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSgoogle-guest-agentpkg:deb/ubuntu/google-guest-agent?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSsnapdpkg:deb/ubuntu/snapd?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 26.04 LTSgolang-go.cryptopkg:deb/ubuntu/golang-go.crypto?arch=source&distro=esm-apps/resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10golang-go.cryptopkg:deb/ubuntu/golang-go.crypto?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10google-guest-agentpkg:deb/ubuntu/google-guest-agent?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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
- ubuntu.com/security/CVE-2026-39834 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-39834 (opens in a new tab)
- go.dev/issue/79567 (opens in a new tab)
- groups.google.com/g/golang-announce/c/a082jnz-LvI (opens in a new tab)
- go.dev/cl/781663 (opens in a new tab)
- pkg.go.dev/vuln/GO-2026-5020 (opens in a new tab)
- github.com/golang/crypto/commit/e052873987615dc96fe67607a9a6adb76311344f (opens in a new tab)
- ubuntu.com/security/notices/USN-8447-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8447-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8447-3 (opens in a new tab)