In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled
When the TLC notification disables AMSDU for a TID, the MLD driver sets
max_tid_amsdu_len to the sentinel value 1. The TSO segmentation path in
iwl_mld_tx_tso_segment() checks for zero but not for this sentinel,
allowing it to reach the num_subframes calculation:
num_subframes = (max_tid_amsdu_len + pad) / (subf_len + pad)
= (1 + 2) / (1534 + 2) = 0
This zero propagates to iwl_tx_tso_segment() which sets:
gso_size = num_subframes * mss = 0
Calling skb_gso_segment() with gso_size=0 creates over 32000 tiny
segments from a single GSO skb. This floods the TX ring with ~1024
micro-frames (the rest are purged), creating a massive burst of TX
completion events that can lead to memory corruption and a subsequent
use-after-free in TCP's retransmit queue (refcount underflow in
tcp_shifted_skb, NULL deref in tcp_rack_detect_loss).
The MVM driver is immune because it checks mvmsta->amsdu_enabled before
reaching the num_subframes calculation. The MLD driver has no equivalent
bitmap check and relies solely on max_tid_amsdu_len, which does not
catch the sentinel value.
Fix this by detecting the sentinel value (max_tid_amsdu_len == 1) at the
existing check and falling back to non-AMSDU TSO segmentation. Also add
a WARN_ON_ONCE guard after the num_subframes division as defense-in-depth
to catch any future code paths that produce zero through a different
mechanism.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). 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: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: 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 total (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)3 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (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