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CVE-2026-98550VulnerabilityPublished Updated

Microsoft · tipc: reject invalid and unexpected GRP_ACK_MSG to prevent bc_ackers underflow

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-98550· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in edc6593c442278fceff0120e8cc58bc592168c35 : patch Microsoft soon.

Data as of 2 Nov 2026, 08:46 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Linux)CVSS 3.17.5
Patch
Available – fixed in edc6593c442278fceff0120e8cc58bc592168c35, b0e517961f09b9f60d338d1ea4e17aacdbf206f0, 507a27435b2bb1f22e3a3674f6a6553eb815021b +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < edc6593c442278fceff0120e8cc58bc592168c35
Fixed in
  • edc6593c442278fceff0120e8cc58bc592168c35
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < b0e517961f09b9f60d338d1ea4e17aacdbf206f0
Fixed in
  • b0e517961f09b9f60d338d1ea4e17aacdbf206f0
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < 507a27435b2bb1f22e3a3674f6a6553eb815021b
Fixed in
  • 507a27435b2bb1f22e3a3674f6a6553eb815021b
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < 478fb08d0c2a53002a721d22b8d6681ec971d90f
Fixed in
  • 478fb08d0c2a53002a721d22b8d6681ec971d90f
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < 99cc2a62e07a44a22254d7beca9ef1f8ad886d0d
Fixed in
  • 99cc2a62e07a44a22254d7beca9ef1f8ad886d0d
LinuxLinuxAffected
  • ≥ 2f487712b89376fce267223bbb0db93d393d4b09, < 80a9ccfc24d3776ef6753a57315e726475fac7d7
Fixed in
  • 80a9ccfc24d3776ef6753a57315e726475fac7d7

Description

CVE-2026-98550 is a vulnerability involving the tipc protocol where invalid and unexpected GRP_ACK_MSG messages are not properly rejected, potentially leading to a bc_ackers underflow condition. The affected Microsoft product versions are 3.0 and 4.0. No CVSS score or detailed impact information is provided.

References

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