CVE-2026-56853: Go standard library net/http · Unthrottled Resource Allocation
Affects Go standard library net/httpSource CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in 1.27.0-rc.3 : patch Go standard library net/http soon.
Data as of 12 Nov 2026, 23:24 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.27.0-rc.3, 1.26.6, 1.25.13
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Aug 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 13 Nov 2026.
What to do
Upgrade Go standard library net/http to 1.27.0-rc.3, 1.26.6 or 1.25.13.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Go standard librarynet/http | Affected
| Fixed in
|
| Go standard librarynet/http | Affected
| Fixed in
|
| Go standard librarynet/http | Affected
| Fixed in
|
Gonet/httppkg:golang/net/httpOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, consider disabling unencrypted HTTP/2 support or implementing external connection rate limiting to mitigate resource exhaustion risks.
Description
CVE-2026-56853 is a high-severity vulnerability in the Go standard library net/http package. It occurs when a server supports unencrypted HTTP/2 and reads initial bytes from new connections to detect the HTTP/2 client preface. During this process, the ReadHeaderTimeout setting is not applied as expected, leading to allocation of resources without proper limits or throttling. This can cause denial of service by exhausting server resources.