HTTP/2 server crash due to HPACK encoder race 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
HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.
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
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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-2026-6617
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-2026-6617
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
HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.
References
5 sourcesInside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
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