CVE-2026-77528

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory (severity: MODERATE) published 2026-09-22. A secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-83415 (ENISA EUVD) · GHSA-hxp9-w8x3-p566 (GitHub Security Advisories) · PYSEC-2026-4027 (OSV.dev) · PYSEC-2026-4031 (OSV.dev)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. Prior to 26.7.1, WebSocket endpoints that accept permessage-deflate and rely on maxMessagePayloadSize enforce that limit against the compressed frame length before inflation but do not recheck the decompressed message size before delivery. A remote unauthenticated client can send a valid compressed frame below the configured wire-size limit that expands beyond the application message limit, causing oversized data to be allocated, joined, validated, and passed to application callbacks. This can create resource-exhaustion pressure, but the advisory does not establish confidentiality or integrity impact. This issue is fixed in version 26.7.1.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 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 partial (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
0.5%
EPSS %ILE
44th
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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: 14 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 partial (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)14 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 partial (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

September 18, 2026

Last Modified

September 24, 2026

Advisory Details (4)

Auto-updated Sep 18, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
GitHub release Patch Available

Release v26_7_1

Patch available: crossbario/autobahn-python v26_7_1

https://github.com/crossbario/autobahn-python/releases/tag/v26_7_1
GitHub commit

commit 77d323a30b09 (crossbario/autobahn-python)

Fix landed in crossbario/autobahn-python commit 77d323a30b09 — awaiting tagged release

https://github.com/crossbario/autobahn-python/commit/77d323a30b09b1828ad8be2ce6344e056970e613
GitHub pull request

Fix 1909

Fix merged in crossbario/autobahn-python PR #1916 on 2026-07-14 — awaiting tagged release

https://github.com/crossbario/autobahn-python/pull/1916
GitHub advisoryMentions a patch (unverified)

Autobahn Python permessage-deflate bypasses maxMessagePayloadSize after inflation · Advisory · crossbario/autobahn-python · GitHub

https://github.com/crossbario/autobahn-python/security/advisories/GHSA-hxp9-w8x3-p566

Vendor Advisories for CVE-2026-77528(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
pipautobahn @ 26.7.1 (fixes < 26.7.1)—ghsa

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

(5 across 4 ecosystems)
PyPI(2)
PackageVulnerable rangeFix by version rangeDependents
autobahn0.10.0 ... 26.6.2 (160 versions)
  • every version up to 26.7.1: fixed in 26.7.1
—
crossbar0.10.0 ... 26.6.1 (109 versions)
  • every version up to 26.7.1: fixed in 26.7.1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
python-autobahn22.7.1+dfsg1-2 ... 24.4.2+dfsg1-5 (10 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python-autobahn23.1.2+dfsg1-2 ... 24.4.2+dfsg1-5 (6 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
python-autobahn23.1.2+dfsg1-2 ... 24.4.2+dfsg1-5 (6 versions)
  • every version on: no fix on record
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 45× 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 it from the CNA feed. 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). Most recent first.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  2. 2026-11-01 07:38 UTCGHSA enrichmentGHSA-hxp9-w8x3-p566 · GitHub severity MODERATE · GitHub CVSS 5.3
  3. 2026-11-01 07:38 UTCEG score recompute
  4. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  5. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  6. 2026-10-30 04:55 UTCOSV refresh
  7. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  8. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  9. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  10. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-10-25 14:01 UTCEG score recompute
  13. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  15. 2026-10-22 18:21 UTCEG score recompute
  16. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  17. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  20. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  21. 2026-10-18 03:12 UTCEG score recompute
  22. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  23. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  24. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  25. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
Show 48 more
  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  3. 2026-10-12 15:37 UTCEG score recompute
  4. 2026-10-11 19:23 UTCEG score recompute
  5. 2026-10-11 16:39 UTCEG score recompute
  6. 2026-10-11 13:58 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  9. 2026-10-10 17:31 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  11. 2026-10-08 17:34 UTCEG score recompute
  12. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  14. 2026-10-06 18:03 UTCEG score recompute
  15. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  16. 2026-10-05 18:25 UTCEG score recompute
  17. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  18. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-03 18:48 UTCEG score recompute
  20. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  21. 2026-10-02 18:43 UTCEG score recompute
  22. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  23. 2026-09-30 19:27 UTCEG score recompute
  24. 2026-09-29 19:51 UTCEG score recompute
  25. 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  26. 2026-09-28 20:11 UTCEG score recompute
  27. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  28. 2026-09-27 20:32 UTCEG score recompute
  29. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  30. 2026-09-26 20:55 UTCEG score recompute
  31. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  32. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  33. 2026-09-24 21:38 UTCEG score recompute
  34. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  35. 2026-09-24 13:36 UTCEG score recompute
  36. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  37. 2026-09-23 14:00 UTCEG score recompute
  38. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  39. 2026-09-22 14:22 UTCEG score recompute
  40. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  41. 2026-09-21 14:46 UTCEG score recompute
  42. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  43. 2026-09-20 15:05 UTCEG score recompute
  44. 2026-09-19 15:28 UTCEG score recompute
  45. 2026-09-19 14:25 UTCEG score recompute
  46. 2026-09-18 20:30 UTCEG score recompute
  47. 2026-09-18 19:49 UTCEG score recomputeFirst assessed: 5.3 MEDIUM
  48. 2026-09-18 19:49 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-77528?
CVE-2026-77528 is a medium-severity vulnerability; its CVE record was published on September 18, 2026. Autobahn Python is a WebSocket and WAMP implementation for Python that supports Twisted and asyncio. Prior to 26.7.1, WebSocket endpoints that accept permessage-deflate and rely on maxMessagePayloadSize enforce that limit against the compressed frame length before inflation but do not recheck the…
When was the CVE record for CVE-2026-77528 published?
The CVE record for CVE-2026-77528 was published on September 18, 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 September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-77528 actively exploited?
CVE-2026-77528 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77528?
CVE-2026-77528 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-77528?
A fix for CVE-2026-77528 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-77528 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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