tls: rx: restore msg_iter before TLS 1.3 optimistic retry
CVE-2026-74611 · published 22 Aug 2026
How serious is it
- Severity: critical, CVSS score 9.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-74611?
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Who is affected
- Linux Linux: ce61327ce989b63c0bd1cc7afee00e218ee696ac to < c71bacacd59166adbea423a04e7474b0e8245b84, ce61327ce989b63c0bd1cc7afee00e218ee696ac to < 3c4e21b1bf8e666a1c141e0f5813ece929570deb, ce61327ce989b63c0bd1cc7afee00e218ee696ac to < 68787940274ec89f41dc91b1a68ee1a16a90735f, ce61327ce989b63c0bd1cc7afee00e218ee696ac to < 3c837266a734e2a22b24d2d567404a501d405835
- Linux Linux: 6.0
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
tls: rx: restore msg_iter before TLS 1.3 optimistic retry
tls_decrypt_sg() advances msg->msg_iter 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, tls_decrypt_sw() 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 TLS_RX_EXPECT_NO_PAD.
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
TLS_RX_EXPECT_NO_PAD enabled and verifies that recvmsg() does not
overwrite later iovecs beyond the returned length.
Check your whole app
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References
- git.kernel.org/stable/c/c71bacacd59166adbea423a04e7474b0e8245b84
- git.kernel.org/stable/c/3c4e21b1bf8e666a1c141e0f5813ece929570deb
- git.kernel.org/stable/c/68787940274ec89f41dc91b1a68ee1a16a90735f
- git.kernel.org/stable/c/3c837266a734e2a22b24d2d567404a501d405835
- git.kernel.org/stable/c/1c8629651cb54f7b51db8fc0b1a9944e4a4b0f5e
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON