Bug 2516673 (CVE-2026-72330)

Summary: CVE-2026-72330 kernel: net/tls: Consume empty data records in tls_sw_read_sock()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's TLS (Transport Layer Security) implementation. A remote attacker could send specially crafted zero-length TLS application data records. This could cause the system to repeatedly process these empty records, blocking all subsequent legitimate data on the connection and leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-15 06:25:10 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/tls: Consume empty data records in tls_sw_read_sock()

A peer may send a zero-length TLS application_data record; TLS 1.3
explicitly permits these as a traffic-analysis countermeasure (RFC
8446, Section 5.1). After decryption such a record has full_len ==
0. tls_sw_read_sock() hands it to the read_actor, which has no
payload to consume and returns zero. The loop treats a zero return
as backpressure (used <= 0), requeues the skb at the head of
rx_list, and stops. rx_list is serviced head-first on the next
call, so the empty record is dequeued, fails the same way, and is
requeued again; every later record on the connection is blocked
behind it.

tls_sw_recvmsg() does not stall on this: a zero-length data record
copies nothing and falls through to consume_skb(). Mirror that in
the read_sock() path by recognizing an empty data record before
the actor runs, consuming it, and continuing.
Comment 1 Keith Grant 2026-08-18 21:19:59 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081508-CVE-2026-72330-7af5@gregkh/T