vulnerability / NVI-00015025 / Revision 1
webtransport-go: Memory Exhaustion Attack due to Buffering of Unknown Capsules
GitHub lists this reviewed advisory for github.com/quic-go/webtransport-go. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
5.3 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/quic-go/webtransport-go
source listed<= 0.11.0
## Summary An attacker can cause excessive memory allocation in webtransport-go by sending an unknown WebTransport capsule with a large payload. The implementation skips unknown capsules by reading the entire capsule body into memory, instead of draining it without retaining the data. This can lead to memory exhaustion. ## Impact A misbehaving or malicious peer can cause a denial-of-service (DoS) attack against webtransport-go clients or servers by triggering excessive memory allocation, potentially leading to crashes or resource exhaustion. ## Details WebTransport sessions use capsules on the HTTP/3 request stream. Unknown capsule types are ignored, but the capsule body still needs to be consumed before the next capsule can be parsed. webtransport-go used `io.ReadAll` when skipping unknown capsules. Since the capsule reader is only limited by the capsule's declared length, a peer could send a large unknown capsule and cause the receiver to allocate memory for the full capsule body. QUIC flow control limits buffered data, but it does not bound total allocation here, since reading the stream advances the flow control window while retaining the received bytes in memory. ## Th
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-g35j-m5xg-vh3q ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.