CVE-2026-80842

UNRATEDCVSS · not yet scored

Also known asEUVD-2026-71292 (ENISA EUVD) · GHSA-4rr3-fvjp-hj2g (GitHub Security Advisories)Source: ENISA EUVD

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EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS v2: —Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: mcast: fix use-after-free of a master VLAN's multicast context

br_multicast_toggle_one_vlan() clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before stopping a VLAN's multicast context. That is the teardown handshake: lockless readers gate on the flag through br_multicast_ctx_should_use() -> br_multicast_ctx_vlan_disabled(), so once it is cleared under the lock no reader can arm the context again.

For a master VLAN the handshake never runs. __vlan_del() clears BRIDGE_VLAN_INFO_BRENTRY before calling br_vlan_put_master(), so br_multicast_toggle_one_vlan(masterv, false) returns early on !br_vlan_is_brentry(vlan): the flag stays set and br->multicast_lock is never taken. br_vlan_put_master() then drains the context in br_multicast_ctx_deinit() and frees the VLAN through call_rcu(), while a reader still inside rcu_read_lock() sees the context as enabled and re-arms it. The port and port-VLAN branch of the function has no br_vlan_is_brentry() test and flips the flag under br->multicast_lock, so it is not affected.

The reader is the bridge transmit path. For a master VLAN br_multicast_rcv() selects brmctx = &vlan->br_mcast_ctx with pmctx = NULL, so IGMP sent to the bridge device re-arms the context's timers after br_multicast_ctx_deinit() has already stopped them.

BUG: KASAN: slab-use-after-free in detach_if_pending+0x412/0x4a0 Write of size 8 at addr ffff88810ac39918 by task brmc/601 __mod_timer+0x51a/0xc50 br_multicast_host_join+0x25b/0x390 __br_multicast_add_group+0x468/0x530 br_ip4_multicast_add_group+0x1a0/0x260 br_multicast_rcv+0x2cda/0x61e0 br_dev_xmit+0x6c4/0x1540 Allocated by task 610: br_vlan_add+0x111/0xb40 br_vlan_info+0x370/0x3e0 Freed by task 0: kfree+0x1a7/0x4f0 rcu_core+0x7dc/0x10a0

Only test br_vlan_is_brentry() when enabling, like the br_multicast_ctx_vlan_global_disabled() test next to it. Disabling then always clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before br_multicast_ctx_deinit() drains the context.

CVSS
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

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

EG Severity
Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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
No SSVC decision: EchelonGraph has not assessed this CVECISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the BOD 26-04 block below.

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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 4, 2026

Last Modified

October 19, 2026

References (8)

Vendor Advisories for CVE-2026-80842(6)

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
linuxKernel @ 5.15.220 (fixes >=5.15.0)—osv

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

(4 across 3 ecosystems)
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (56 versions)
  • every version up to 6.1.187-1: fixed in 6.1.187-1
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linux-6.126.12.100-1~deb12u1, 6.12.101-1~deb12u1, 6.12.107-1~deb12u1
  • every version up to 6.12.111-1~deb12u1: fixed in 6.12.111-1~deb12u1
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Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 6.12.96-1 (35 versions)
  • every version up to 6.12.111-1: fixed in 6.12.111-1
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Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (173 versions)
  • every version up to 7.1.13-1: fixed in 7.1.13-1
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Data Freshness Timeline

(refreshed 7× in last 7d / 34× 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 → 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.

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. 2 repeat rows among the latest 100 are merged into the row they repeat.

  1. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  2. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  3. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  4. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  5. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  6. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  7. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  8. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  9. 2026-11-04 16:37 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  10. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  11. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  12. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  13. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  14. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  15. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  16. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  17. 2026-10-28 07:55 UTCOSV refresh
  18. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  19. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  20. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  21. 2026-10-25 13:59 UTCEchelonGraph re-scored
  22. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  23. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  24. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  25. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
Show 73 more
  1. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  2. 2026-10-19 09:25 UTCNVD update
  3. 2026-10-19 09:23 UTCEchelonGraph re-scored
  4. 2026-10-19 09:23 UTCVendor advisory
  5. 2026-10-19 09:23 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  6. 2026-10-19 08:58 UTCMITRE cvelistV5
  7. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  8. 2026-10-18 03:09 UTCEchelonGraph re-scored
  9. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  10. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  11. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  12. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  13. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  14. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  15. 2026-10-12 14:57 UTCEchelonGraph re-scored
  16. 2026-10-11 19:21 UTCEchelonGraph re-scored
  17. 2026-10-11 16:37 UTCEchelonGraph re-scored
  18. 2026-10-11 13:55 UTCEchelonGraph re-scored
  19. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  20. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  21. 2026-10-09 05:23 UTCVendor advisory
  22. 2026-10-09 05:23 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  23. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  24. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  25. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  26. 2026-10-06 08:59 UTCVendor advisory
  27. 2026-10-06 08:58 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  28. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  29. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  30. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  31. 2026-10-03 12:35 UTCVendor advisory
  32. 2026-10-03 12:35 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  33. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  34. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  35. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  36. 2026-09-30 11:18 UTCEchelonGraph re-scored
  37. 2026-09-30 11:18 UTCVendor advisory
  38. 2026-09-30 11:18 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  39. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  40. 2026-09-27 14:15 UTCVendor advisory
  41. 2026-09-27 14:15 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  42. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  43. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  44. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  45. 2026-09-24 17:12 UTCVendor advisory
  46. 2026-09-24 17:12 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  47. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  48. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  49. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  50. 2026-09-21 20:49 UTCVendor advisory
  51. 2026-09-21 20:49 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  52. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  53. 2026-09-19 00:25 UTCVendor advisory
  54. 2026-09-19 00:25 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  55. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  56. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  57. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  58. 2026-09-16 04:02 UTCVendor advisory
  59. 2026-09-16 04:01 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  60. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  61. 2026-09-13 07:36 UTCVendor advisory
  62. 2026-09-13 07:36 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  63. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  64. 2026-09-10 11:12 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  65. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  66. 2026-09-07 14:40 UTCEchelonGraph re-scored
  67. 2026-09-07 14:40 UTCVendor advisory
  68. 2026-09-07 14:40 UTCGHSA enrichmentGHSA-4rr3-fvjp-hj2g
  69. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  70. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  71. 2026-09-04 16:22 UTCNVD update
  72. 2026-09-04 16:05 UTCEchelonGraph re-scored
  73. 2026-09-04 16:04 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-80842?
CVE-2026-80842 is a vulnerability whose severity is not yet rated; its CVE record was published on September 4, 2026. In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: fix use-after-free of a master VLAN's multicast context br_multicast_toggle_one_vlan() clears BR_VLFLAG_MCAST_ENABLED under br->multicast_lock before stopping a VLAN's multicast context. That is the teardown…
When was the CVE record for CVE-2026-80842 published?
The CVE record for CVE-2026-80842 was published on September 4, 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 19, 2026; the record at its source may have been updated since.
Is CVE-2026-80842 actively exploited?
CVE-2026-80842 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-80842?
A fix for CVE-2026-80842 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-80842 are linked in the Vendor Advisories panel on this page.

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