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CVE-2026-80839

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Last modified

CVE-2026-80839 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: batman-adv: reject unrepresentable multicast TVLV offsets The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable. If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32.

Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: reject unrepresentable multicast TVLV offsets The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable. If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32. batadv_mcast_forw_packet() consequently accepts an oversized multicast tracker and accesses memory beyond the skb data. Add skb_set_transport_header_careful(), an offset-aware counterpart to skb_reset_transport_header_careful(), which validates the final head-relative offset before assigning it. Use the new helper in batadv_tvlv_call_handler() and reject unrepresentable TVLVs before setting the network header.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 07afe1ba288c04280622fa002ed385f1ac0b6fe6, < da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2; >= 07afe1ba288c04280622fa002ed385f1ac0b6fe6, < 916ec741e65af072b98e475feaad98c063da1b7c; >= 07afe1ba288c04280622fa002ed385f1ac0b6fe6, < 1b466746fe109127fd983100a228cdd1f1f6ece2; >= 07afe1ba288c04280622fa002ed385f1ac0b6fe6, < 2b46baa591d0a7c16b62f150917187e70d053be6; >= 07afe1ba288c04280622fa002ed385f1ac0b6fe6, < f12c2de4f542e3220e17e0606f492110064f04cb
LinuxLinux6.8

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-80839?
In the Linux kernel, the following vulnerability has been resolved: batman-adv: reject unrepresentable multicast TVLV offsets The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable. If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32. batadv_mcast_forw_packet() consequently accepts an oversized multicast tracker and accesses memory beyond the skb data. Add skb_set_transport_header_careful(), an offset-aware counterpart to skb_reset_transport_header_careful(), which validates the final head-relative offset before assigning it. Use the new helper in batadv_tvlv_call_handler() and reject unrepresentable TVLVs before setting the network header.
How severe is CVE-2026-80839?
Severity scoring for CVE-2026-80839 is pending analysis.
How do I fix CVE-2026-80839?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST