CVE-2026-46193
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
xfrm: ah: account for ESN high bits in async callbacks
AH allocates its temporary auth/ICV layout differently when ESN is enabled: the async ahash setup appends a 4-byte seqhi slot before the ICV or auth_data area, but the async completion callbacks still reconstruct the temporary layout as if seqhi were absent.
With an async AH implementation selected, that makes AH copy or compare the wrong bytes on both the IPv4 and IPv6 paths. In UML repro on IPv4 AH with ESN and forced async hmac(sha1), ping fails with 100% packet loss, and the callback logs show the pre-fix drift:
Leer descripción completaMostrar menos
Reconstruct the callback-side layout the same way the setup path built it by skipping the ESN seqhi slot before locating the saved auth_data or ICV. Per RFC 4302, the ESN high-order 32 bits participate in the AH ICV computation, so the async callbacks must account for the seqhi slot.
Post-fix, the same IPv4 AH+ESN+forced-async-hmac(sha1) UML repro shows the corrected offset (ah4 output_done: esn=1 err=0 icv_off=24 expected_off=24) and ping succeeds; net/ipv4/ah4.o and net/ipv6/ah6.o build clean at W=1. IPv6 AH+ESN was not exercised at runtime, and the change has not been tested against a real async hardware AH engine.
Detalles técnicos trazas, registros y código del informe original
ah4 output_done: esn=1 err=0 icv_off=20 expected_off=24 ah4 input_done: esn=1 auth_off=20 expected_auth_off=24 icv_off=32 expected_icv_off=36
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.16%
- Percentil entre todas las CVEs puntuadas: 5
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/0555d4f526232b3c9e3afbcd490c0c0793aefec6
- https://git.kernel.org/stable/c/1dae77078ceb4bab833f7a4935f05c5b8c97b9ba
- https://git.kernel.org/stable/c/2ffaa7a94f9a4d22724364a1821735a0231d9f8d
- https://git.kernel.org/stable/c/729899a2aa8bda7844be0cdcd3b470f11b912eda
- https://git.kernel.org/stable/c/7db99a09b3bc87268287bc7ab5f2e7f382b5ad87
- https://git.kernel.org/stable/c/ec406c26c97594124e79d14516b729a8d5dced62
- https://git.kernel.org/stable/c/ec54093e6a8f87e800bb6aa15eb7fc1e33faa524
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: ah: account for ESN high bits in async callbacks\n\nAH allocates its temporary auth/ICV layout differently when ESN is enabled:\nthe async ahash setup appends a 4-byte seqhi slot before the ICV or\nauth_data area, but the async completion callbacks still reconstruct the\ntemporary layout as if seqhi were absent.\n\nWith an async AH implementation selected, that makes AH copy or compare\nthe wrong bytes on both the IPv4 and IPv6 paths. In UML repro on IPv4 AH\nwith ESN and forced async hmac(sha1), ping fails with 100% packet loss,\nand the callback logs show the pre-fix drift:\n\n ah4 output_done: esn=1 err=0 icv_off=20 expected_off=24\n ah4 input_done: esn=1 auth_off=20 expected_auth_off=24 icv_off=32 expected_icv_off=36\n\nReconstruct the callback-side layout the same way the setup path built it\nby skipping the ESN seqhi slot before locating the saved auth_data or ICV.\nPer RFC 4302, the ESN high-order 32 bits participate in the AH ICV\ncomputation, so the async callbacks must account for the seqhi slot.\n\nPost-fix, the same IPv4 AH+ESN+forced-async-hmac(sha1) UML repro shows\nthe corrected offset (ah4 output_done: esn=1 err=0 icv_off=24\nexpected_off=24) and ping succeeds; net/ipv4/ah4.o and net/ipv6/ah6.o\nbuild clean at W=1. IPv6 AH+ESN was not exercised at runtime, and the\nchange has not been tested against a real async hardware AH engine."
}
],
"lastModified": "2026-09-08T09:18:08.903",
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