CVE-2026-98852 Detección de encabezados de extensión IPv6 en paquetes tunelizados en el kernel de Linux

Afectados

• Linux

  desde ed71cf465c75f5688b07a35d373cd1d6b589c8ea hasta antes de fdbd83c2d929ec968b37d2f75149a79440e328ffdesde 33670f780e0120c3dacda188c512bbffe0b6044c hasta antes de 44ba9dc568c878b699d05e7cf699572dc9df4b59desde a98b78116a27e2a57b696b569b2cb431c95cf9b6 hasta antes de aa480f05aed7a9eee87d4a6fc90647fe9679c670desde c4336a07eb6b2526dc2b62928b5104b41a7f81f5 hasta antes de cabacdf98e09eb74599c4d97d7bd7fd659598fb7desde c4336a07eb6b2526dc2b62928b5104b41a7f81f5 hasta antes de 5f0764cb1c81a9712bce605d38efe6d844a70b292094a7cf91b71367b649f991aacc7b579f793d0b732fdeb2987c94b439d51f5cb9addddc2fc48c42desde 6.6.134 hasta antes de 6.6.160desde 6.12.81 hasta antes de 6.12.113desde 6.18.22 hasta antes de 6.18.56desde 6.1.168 hasta antes de 6.2desde 6.19.12 hasta antes de 6.20

• Linux

  7.0

Qué hacer

1. Verificá si usás Linux y en qué versión.
2. Actualizá a la versión corregida que indique el fabricante en su aviso o aplicá su mitigación.
3. Revisá registros y accesos de los sistemas expuestos para descartar un uso previo.

Calculadora CVSS

Esta vulnerabilidad todavía no tiene vector CVSS publicado.

Descripción original

In the Linux kernel, the following vulnerability has been resolved: net: extend IPv6 exthdr detection of tunneled packets Commit c4336a07eb6b ("net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback") split skb_gso_has_extension_hdr() into mutually exclusive branches on skb->encapsulation. This did not yet address all paths: 1. With skb->encapsulation set, the outer header is not checked. IPv6 tunnels such as ip6_gre and ip6_tunnel add an outer Destination Options header by default (encap_limit). Their GSO packets skip software GSO, then skb_csum_hwoffload_help() sees the outer extension header and calls skb_checksum_help() on the GSO skb, which warns and drops it. 2. Tunnels over IPv6 without an outer transport header, such as ip6_tunnel, leave skb->transport_header at the inner transport header. skb_network_header_len() then spans the outer IPv6, tunnel and inner IP headers, a false positive. 3. UDP tunnels without an inner network header, such as SCTP-in-UDP or PSP, have no inner IPv6 header to check. Decide on the outer header alone. 4. Directly dereferencing inner_ip_hdr(skb)->version without skb_header_pointer() is unsafe. Instead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if set, on the inner IPv6 header. Read the headers with skb_header_pointer(). Keep the skb_network_header_len() check when !skb->encapsulation to also catch encapsulated packets without skb->encapsulation (e.g., virtio). Use the same helper in skb_csum_hwoffload_help(). Its open coded test has the false positive of (2) and ignores the inner header. Background: checksum offload of tunneled packets invariants: Non-GSO skb: - If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes the outer checksum in software and the device offloads only the inner L4 checksum. - If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP, Remote Checksum Offload), the device offloads the outer UDP or GRE checksum instead. GSO skb: - A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM computes both inner and outer checksums per segment. The outer checksum is seeded with only the pseudo-header checksum. A NETIF_F_IPV6_CSUM device must parse through the outer headers to reach the inner ones.

Referencias (5)

• git.kernel.org/stable/c/fdbd83c2d929ec968b37d2f75149a79440e328ff
• git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59
• git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670
• git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7
• git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29

Resumen traducido automáticamente de la descripción original. Fuente: Nureq Monitor. Cómo funciona.