Double flow control refund on HTTP/2 server streams in net/http
Severity and exploitation
KEV coverage does not rule out exploitation.
Severity
unknownCVSS measures technical severity, not the likelihood of an attack.
Known exploitation
Not listed in the checked CISA KEV catalog
Absence from CISA KEV does not rule out attacks.
Public exploit
Not established by this record
Missing evidence does not mean no public exploit exists.
Remediation
Package fixes recorded
Fix versions are recorded for 2 of 2 mapped packages. Check each release branch and any separate product guidance.
What this means
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
Source excerpt · OSVAttack conditions
No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.
Review supporting sources →Affected versions
Check the exact model, release, and any platform requirements against your installation.
Packages
Compare each installed version with the publisher’s affected ranges. Where a fix is recorded, choose the appropriate release branch and test compatibility before upgrading.
| Affected range | Recorded fix |
|---|---|
| Earlier releases before 1.26.9Semantic versions | 1.26.9 |
| From 1.27.0-0 before 1.27.2Semantic versions | 1.27.2 |
Version evidence: OSV · GO-2026-6612
View original version evidence (0 explicit versions)
| Affected range | Recorded fix |
|---|---|
| Earlier releases before 0.60.0Semantic versions | 0.60.0 |
Version evidence: OSV · GO-2026-6612
View original version evidence (0 explicit versions)
What to do
Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.
Use the recorded fix for your release branch. Review the publisher’s instructions and test compatibility before upgrading.
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Public exploit evidence
No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.
Original source description
Read the full publisher description
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
References
5 sourcesInside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
No official CVE record has been imported. Use the source links below for the original advisory.
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