CVE-2026-78663

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.1 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.9% (58th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from CISA-ADP (Vulnrichment) CVSS v3.1
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS

Also known asEUVD-2026-95427 (ENISA EUVD) · GO-2026-6612 (OSV.dev)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.9%CVSS: 9.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
56
EG Risk 56/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.9% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.9%
EPSS %ILE
58th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.CISA-ADP (Vulnrichment) CVSS v3.1 · CVSS v3.1
EG Likelihood
0.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 8, 2026

Last Modified

October 9, 2026

Advisory Details (6)

Auto-updated Oct 9, 2026
Patch available.
Web page

GO-2026-6612 - Go Packages

https://pkg.go.dev/vuln/GO-2026-6612
Web page

net/http: double flow control refund on HTTP/2 server streams · Issue #81743 · golang/go · GitHub

https://go.dev/issue/81743

Patch Availability(16)

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(12 across 5 ecosystems)
Debian:14(4)
PackageVulnerable rangeFix by version rangeDependents
golang-1.251.25.0-1 ... 1.25.9-1 (20 versions)
  • every version on: no fix on record
—
golang-1.261.26.0-1 ... 1.26~rc3-2 (23 versions)
  • every version up to 1.26.9-1: fixed in 1.26.9-1
—
golang-1.271.27.0-1 ... 1.27~rc3-1 (9 versions)
  • every version up to 1.27.2-1: fixed in 1.27.2-1
—
golang-golang-x-net1:0.27.0-2 ... 1:0.58.0-1 (10 versions)
  • every version up to 1:0.60.0-1: fixed in 1:0.60.0-1
—
Alpine:v3.24(2)
PackageVulnerable rangeFix by version rangeDependents
docker—
  • every version up to 29.9.0-r0: fixed in 29.9.0-r0
—
go—
  • every version up to 1.26.9-r0: fixed in 1.26.9-r0
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
golang-1.191.19.10-1 ... 1.19.9-1 (12 versions)
  • every version on: no fix on record
—
golang-golang-x-net1:0.10.0-1 ... 1:0.7.0+dfsg-1 (28 versions)
  • every version on: no fix on record
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
golang-1.241.24.12-1 ... 1.24.9-1 (10 versions)
  • every version on: no fix on record
—
golang-golang-x-net1:0.27.0-2 ... 1:0.60.0-1 (11 versions)
  • every version on: no fix on record
—
Go(2)
PackageVulnerable rangeFix by version rangeDependents
golang.org/x/net—
  • every version up to 0.60.0: fixed in 0.60.0
—
stdlib—
  • every version up to 1.26.9: fixed in 1.26.9
  • 1.27.0-0 up to 1.27.2: fixed in 1.27.2
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 14× in last 7d / 59× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 109 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 9 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 01:10 UTCEchelonGraph re-scored
  2. 2026-11-13 01:10 UTCVendor advisory
  3. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  4. 2026-11-12 03:09 UTCEchelonGraph re-scored
  5. 2026-11-12 03:09 UTCVendor advisory
  6. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  7. 2026-11-11 05:10 UTCEchelonGraph re-scored
  8. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  9. 2026-11-10 07:11 UTCEchelonGraph re-scored
  10. 2026-11-10 07:11 UTCVendor advisory
  11. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  12. 2026-11-09 09:10 UTCEchelonGraph re-scored
  13. 2026-11-09 09:10 UTCVendor advisory
  14. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  15. 2026-11-08 11:11 UTCEchelonGraph re-scored
  16. 2026-11-08 11:11 UTCVendor advisory
  17. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  18. 2026-11-07 13:13 UTCEchelonGraph re-scored
  19. 2026-11-07 13:13 UTCVendor advisory
  20. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  21. 2026-11-06 15:10 UTCVendor advisory
  22. 2026-11-05 17:11 UTCEchelonGraph re-scored
  23. 2026-11-05 17:11 UTCVendor advisory
  24. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  25. 2026-11-04 19:11 UTCEchelonGraph re-scored
Show 75 more
  1. 2026-11-04 19:11 UTCVendor advisory
  2. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  3. 2026-11-03 21:11 UTCEchelonGraph re-scored
  4. 2026-11-03 21:11 UTCVendor advisory
  5. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  6. 2026-11-02 23:12 UTCEchelonGraph re-scored
  7. 2026-11-02 23:12 UTCVendor advisory
  8. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  9. 2026-11-02 01:12 UTCEchelonGraph re-scored
  10. 2026-11-02 01:12 UTCVendor advisory
  11. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  12. 2026-11-01 03:12 UTCEchelonGraph re-scored
  13. 2026-11-01 03:12 UTCVendor advisory
  14. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  15. 2026-10-31 05:13 UTCEchelonGraph re-scored
  16. 2026-10-31 05:13 UTCVendor advisory
  17. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  18. 2026-10-30 07:14 UTCEchelonGraph re-scored
  19. 2026-10-30 07:14 UTCVendor advisory
  20. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  21. 2026-10-29 09:15 UTCEchelonGraph re-scored
  22. 2026-10-29 09:15 UTCVendor advisory
  23. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  24. 2026-10-28 11:17 UTCEchelonGraph re-scored
  25. 2026-10-28 11:17 UTCVendor advisory
  26. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  27. 2026-10-27 12:44 UTCEchelonGraph re-scored
  28. 2026-10-27 12:44 UTCVendor advisory
  29. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  30. 2026-10-26 14:45 UTCEchelonGraph re-scored
  31. 2026-10-26 14:45 UTCVendor advisory
  32. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  33. 2026-10-25 15:57 UTCVendor advisory
  34. 2026-10-25 14:00 UTCEchelonGraph re-scored
  35. 2026-10-24 17:55 UTCEchelonGraph re-scored
  36. 2026-10-24 17:55 UTCVendor advisory
  37. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  38. 2026-10-23 19:56 UTCEchelonGraph re-scored
  39. 2026-10-23 19:56 UTCVendor advisory
  40. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  41. 2026-10-22 21:46 UTCEchelonGraph re-scored
  42. 2026-10-22 21:46 UTCVendor advisory
  43. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  44. 2026-10-21 23:45 UTCEchelonGraph re-scored
  45. 2026-10-21 23:45 UTCVendor advisory
  46. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  47. 2026-10-21 01:45 UTCEchelonGraph re-scored
  48. 2026-10-21 01:45 UTCVendor advisory
  49. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  50. 2026-10-20 03:46 UTCEchelonGraph re-scored
  51. 2026-10-20 03:46 UTCVendor advisory
  52. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  53. 2026-10-19 04:32 UTCEchelonGraph re-scored
  54. 2026-10-19 04:32 UTCVendor advisory
  55. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  56. 2026-10-18 06:30 UTCVendor advisory
  57. 2026-10-18 03:11 UTCEchelonGraph re-scored
  58. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  59. 2026-10-17 06:06 UTCEchelonGraph re-scored
  60. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  61. 2026-10-16 07:11 UTCEchelonGraph re-scored
  62. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  63. 2026-10-15 06:00 UTCEchelonGraph re-scored
  64. 2026-10-15 06:00 UTCVendor advisory
  65. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  66. 2026-10-14 01:38 UTCEchelonGraph re-scored
  67. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  68. 2026-10-12 21:48 UTCEchelonGraph re-scored
  69. 2026-10-12 21:48 UTCVendor advisory
  70. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  71. 2026-10-12 15:36 UTCEchelonGraph re-scored
  72. 2026-10-11 19:22 UTCEchelonGraph re-scored
  73. 2026-10-11 16:38 UTCEchelonGraph re-scored
  74. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  75. 2026-10-11 13:42 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2026-78663?
CVE-2026-78663 is a critical-severity vulnerability; its CVE record was published on October 8, 2026. 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…
When was the CVE record for CVE-2026-78663 published?
The CVE record for CVE-2026-78663 was published on October 8, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 9, 2026; the record at its source may have been updated since.
Is CVE-2026-78663 actively exploited?
CVE-2026-78663 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.9% probability of exploitation in the next 30 days (58th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-78663?
CVE-2026-78663 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-78663?
A fix for CVE-2026-78663 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-78663 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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