CVE-2026-99088

UNRATEDCVSS · not yet scoredTrending — 6 sources updated this week

Also known asEUVD-2026-109894 (ENISA EUVD) · GHSA-hwf6-223w-r64q (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: openvswitch: validate transport header presence in set_ipv6_addr

When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header().

update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless.

Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing.

See the syzbot trace:

!skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline] RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline] RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399 [...] Call Trace: set_ipv6 net/openvswitch/actions.c:531 [inline] do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366 ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592 ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800

CVSS v3
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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
6th
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. 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

October 26, 2026

Last Modified

October 30, 2026

References (8)

Vendor Advisories for CVE-2026-99088(2)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 19× 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. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  2. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  3. 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  4. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  5. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  6. 2026-10-30 13:38 UTCVendor advisory
  7. 2026-10-30 13:38 UTCGHSA enrichmentGHSA-hwf6-223w-r64q
  8. 2026-10-30 13:27 UTCNVD update
  9. 2026-10-30 12:51 UTCEG score recompute
  10. 2026-10-30 12:51 UTCVendor advisory
  11. 2026-10-30 12:51 UTCGHSA enrichmentGHSA-hwf6-223w-r64q
  12. 2026-10-30 12:50 UTCMITRE cvelistV5
  13. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  14. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  15. 2026-10-27 16:33 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  16. 2026-10-26 16:01 UTCENISA EUVD ID recordedEUVD-2026-109894 · Source: ENISA EUVD
  17. 2026-10-26 15:26 UTCNVD update
  18. 2026-10-26 15:03 UTCEG score recompute
  19. 2026-10-26 15:00 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-99088?
CVE-2026-99088 is a vulnerability whose severity is not yet rated; its CVE record was published on October 26, 2026. In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: validate transport header presence in set_ipv6_addr When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6…
When was the CVE record for CVE-2026-99088 published?
The CVE record for CVE-2026-99088 was published on October 26, 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 30, 2026; the record at its source may have been updated since.
Is CVE-2026-99088 actively exploited?
CVE-2026-99088 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (6th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-99088?
A fix for CVE-2026-99088 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-99088 are linked in the Vendor Advisories panel on this page.

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