UBUNTU-CVE-2026-74611: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: tls: rx: restore msgiter before TLS 1.3 optimistic retry tlsdecryptsg() advances msg->msgiter when it maps user pages for the optimistic TLS 1.3 zero-copy path. If the decrypted record turns out not to be unpadded application data, tlsdecryptsw() retries into a kernel skb, but leaves the iterator advanced. The subsequent copy from the skb then writes decrypted bytes again at a later point in the caller iovecs while recvmsg() reports only the post-retry length. A TLS peer can trigger this after the receiver enables TLSRXEXPECTNOPAD. Revert the iterator by the number of bytes consumed by the optimistic mapping before retrying without zero-copy. Add a selftest which sends a TLS 1.3 control record with TLSRXEXPECTNOPAD enabled and verifies that recvmsg() does not overwrite later iovecs beyond the returned length.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1036.39 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
Restore msg->msg_iter by the number of bytes consumed by the optimistic TLS 1.3 zero-copy mapping before retrying tls_decrypt_sw() without zero-copy; add a selftest that enables TLS_RX_EXPECT_NO_PAD, sends a TLS 1.3 control record, and verifies recvmsg() does not overwrite later iovecs beyond the returned length.
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
Systems using the affected Ubuntu Linux kernel packages are exposed only when an application uses kernel TLS receive processing for TLS 1.3 and enables TLS_RX_EXPECT_NO_PAD. The issue is triggered by a TLS peer sending a record that is not unpadded application data during the optimistic zero-copy receive path.
What can a remote attacker do?
A TLS peer can cause decrypted bytes to be written into later locations in the receiving application's iovec buffers, beyond the length reported by recvmsg(). The reported impact is integrity-only; no confidentiality or availability impact is listed.
Is a default configuration affected?
The provided information identifies TLS_RX_EXPECT_NO_PAD as a prerequisite. It does not establish that this option is enabled by default.
How can I determine whether an application may be affected?
Review applications that use kernel TLS receive processing and TLS 1.3 for use of the TLS_RX_EXPECT_NO_PAD socket option, particularly those using recvmsg() with multiple iovec buffers. Affected behavior involves a TLS 1.3 control record causing data beyond recvmsg()'s returned length to overwrite later iovecs.