CVE-2026-99288

UNRATEDCVSS · not yet scored

Also known asEUVD-2026-121963 (ENISA EUVD) · GHSA-qmmm-94cj-pp32 (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:

inet: reject unhashed sockets during established lookups

TCP established ehash lookups are lockless. The socket caches involved use SLAB_TYPESAFE_BY_RCU, so memory can be reused before an RCU reader that retained its old address has finished.

After a tuple match, __inet_lookup_established() and __inet6_lookup_established() acquire a reference and repeat the tuple check. They do not check whether the new object is hashed. If the address is reused for a socket with the same tuple, the lookup can acquire a reference to the new object and return it while its nulls node is unhashed.

A PoC that drives reuse with a SYN cookie request socket reproduced the crash. The new request socket is unhashed and has a NULL rsk_listener. A lookup that had loaded the address of the old request socket acquired the reference published by tcp_get_cookie_sock() and returned the new object. tcp_v4_rcv() then read sk_state through the NULL listener.

The resulting crash was:

BUG: kernel NULL pointer dereference, address: 0000000000000012 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... Oops: Oops: 0000 [#1] SMP NOPTI CPU: 4 UID: 0 PID: 0 Comm: swapper/4 Not tainted 7.3.0-00591-g0e135910deec #1 PREEMPT(lazy) ... RIP: 0010:tcp_v4_rcv+0x44e/0x1280 ... R10: 0000000000000001 R11: 00000000024ca8c0 R12: 0000000000000000 ... CR2: 0000000000000012 CR3: 0000000103d50004 CR4: 0000000000770ef0 ... Call Trace: ? raw_local_deliver+0xae/0x240 ip_protocol_deliver_rcu+0x2d/0x180 ip_local_deliver_finish+0x84/0x100 ip_sublist_rcv_finish+0x5f/0x70 ip_sublist_rcv+0x12a/0x1d0 ip_list_rcv+0xfd/0x130 __netif_receive_skb_list_core+0x223/0x250 netif_receive_skb_list_internal+0x1d2/0x2c0 ? try_fill_recv+0x39/0x7b0 napi_complete_done+0x74/0x170 virtnet_poll+0x445/0x600 __napi_poll+0x27/0x1e0 net_rx_action+0x2fe/0x3b0 handle_softirqs+0xc2/0x2c0 __irq_exit_rcu+0x74/0xd0 common_interrupt+0x7f/0x90 ... Kernel panic - not syncing: Fatal exception in interrupt

After taking a reference, check whether the nulls node is unhashed in both IPv4 and IPv6 established lookups. If it is unhashed or the tuple no longer matches, drop the reference and restart the lookup.

Lookups racing with the TIME_WAIT hashdance, or with a request being replaced by its child, now restart and find the new socket instead of returning the old one.

Request sockets that were never inserted into ehash can have a nonzero refcount, and a stale lookup can hold a transient reference. Therefore, when SYN cookie, Fast Open, and request migration paths fail after setting a nonzero refcount, release the references held by those paths with reqsk_put() instead of freeing the request directly.

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
4th
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

November 10, 2026

Last Modified

November 10, 2026

References (3)

Vendor Advisories for CVE-2026-99288(2)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 7.3~rc7-1~exp1 (378 versions)
  • every version on: no fix on record
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Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.3~rc7-1~exp1 (200 versions)
  • every version on: no fix on record
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Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.3~rc7-1~exp1 (200 versions)
  • every version on: no fix on record
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Data Freshness Timeline

(refreshed 6× in last 7d / 6× 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.

  1. 2026-11-12 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  2. 2026-11-11 16:41 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  3. 2026-11-11 08:19 UTCGHSA enrichmentGHSA-qmmm-94cj-pp32
  4. 2026-11-10 19:28 UTCNVD update
  5. 2026-11-10 19:05 UTCENISA EUVD ID recordedEUVD-2026-121963 · Source: ENISA EUVD
  6. 2026-11-10 18:29 UTCEchelonGraph re-scored
  7. 2026-11-10 18:26 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-99288?
CVE-2026-99288 is a vulnerability whose severity is not yet rated; its CVE record was published on November 10, 2026. In the Linux kernel, the following vulnerability has been resolved: inet: reject unhashed sockets during established lookups TCP established ehash lookups are lockless. The socket caches involved use SLAB_TYPESAFE_BY_RCU, so memory can be reused before an RCU reader that retained its old address…
When was the CVE record for CVE-2026-99288 published?
The CVE record for CVE-2026-99288 was published on November 10, 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 November 10, 2026; the record at its source may have been updated since.
Is CVE-2026-99288 actively exploited?
CVE-2026-99288 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (4th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-99288?
A fix for CVE-2026-99288 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-99288 are linked in the Vendor Advisories panel on this page.

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