websocket-driver: Resource limit bypass via message compression

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.7.5, if this library is used with the permessage-deflate extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size because the limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression in lib/websocket/driver/hybi.js. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. This issue is fixed in version 0.7.5.

Source published

17 Jul 2026 20:54:22 UTC

Source modified

21 Jul 2026 02:23:58 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.7.5, if this library is used with the permessage-deflate extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size because the limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression in lib/websocket/driver/hybi.js. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. This issue is fixed in version 0.7.5.

Source published

17 Jul 2026 21:17:08 UTC

Source modified

24 Oct 2026 20:10:00 UTC

Observed here

25 Oct 2026 13:17:28 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Impact If this library is used in tandem with the `permessage-deflate` extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size. This is because this limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. ### Patches The issue has been patched in version 0.7.5, by checking the length of messages after they are processed by incoming extensions. All users should upgrade to this version. ### Workarounds No known workarounds exist. ### Acknowledgements This issue was discovered and reported by Pranjali Thakur, DepthFirst Security Research Team.

Source published

15 Jul 2026 22:08:17 UTC

Source modified

10 Sep 2026 03:50:52 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

Publisher rating · MODERATE