9.8

CVE-2026-64037: wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled

Modified
AliasesUBUNTU-CVE-2026-64037DEBIAN-CVE-2026-64037
Published 19-07-2026Last modified 19-10-2026

Vulnerability summary

CVE-2026-64037 is a critical (CVSS 9.8) Improper Input Validation vulnerability in linux. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 37.2% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.43%
0%100%
Low · -0.20 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 10 · Related 8
RHSA-2026:65334RHSA-2026:67150USN-8593-1USN-8603-1USN-8618-1USN-8663-1

Timeline

  1. 19-07-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.43%

Chance of exploitation in the next 30 days

Percentile

37%

Versus all other CVEs

30-day change

Decrease -0.20 pp

From 0.63% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu118 products
  • linux< 7.0.0-28.28
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 7.0.0-1009.9
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ d1e879ec600f9b3bdd253167533959facfefb17b, < 9e360e610a73f62432e986775023d5382773f045 | ≥ d1e879ec600f9b3bdd253167533959facfefb17b, < cbe1c8245e4469d1aa6e12e5d913611376d23788 | ≥ d1e879ec600f9b3bdd253167533959facfefb17b, < 92cee08dc4f00e77fd1317e4343c5d458b0abab7 | 6.15
  • linux_kernel≥ 6.15, < 6.18.34 | ≥ 6.19, < 7.0.11 | 7.1:rc1 | 7.1:rc2 | 7.1:rc3 | 7.1:rc4
Debian1 product
  • linux< 7.0.12-1

3 vendors · 121 products

References

15 links
Show all 15 references