Answer in brief
CVE-2026-97984 records a Unknown severity vulnerability in net: ipv6: Fix UDP length overflow with PMTU discover and big MTU. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=427faee167bce4ccb0b22f6815a9ac509e31d4c3 <1d56a00ec91f2885c64ea5b8cea18cb746b91bbb || >=427faee167bce4ccb0b22f6815a9ac509e31d4c3 <ce66352d3eb21825410af8b91db7cc4bb8e22c98 || >=427faee167bce4ccb0b22f6815a9ac509e31d4c3 <e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc || >=427faee167bce4ccb0b22f6815a9ac509e31d4c3 <0ae10b6be49b425827659b23bcce498f80eb7182 | 1d56a00ec91f2885c64ea5b8cea18cb746b91bbb, ce66352d3eb21825410af8b91db7cc4bb8e22c98, e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc, 0ae10b6be49b425827659b23bcce498f80eb7182 |
| Linux/Linuxgeneric | 5.15 | Not reported |
Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 25, 2026
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: Fix UDP length overflow with PMTU discover and big MTU This commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to avoid a possible overflow of UDP length that triggers a WARN in udp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to IPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over a netdev with an unusually large MTU. Steps to reproduce (included in the new selftest): 1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be set to that MTU in ip6_setup_cork. 2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It lets maxnonfragsize be set to device MTU (cork->fragsize) in __ip6_append_data, rather than to IP6_MAX_MTU. 3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of IPv6 header). Device MTU allows it (it's only one byte bigger than IP6_MAX_MTU, and the device MTU is bigger than that). 4. The UDP length in the built packet is 65536, which overflows the 16-bit length field and triggers the WARN in udp_set_len_short. To avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit the change to UDP sockets only. The original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to predate git history (verified reproduction on 2.6.21), was fixed later, and then reappeared in commit 427faee167bc ("net: ipv6: introduce ip6_dst_mtu_maybe_forward"), which is chosen as the Fixes tag here. The overflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in commit 628a5c561890 ("[INET]: Add IP(V6)_PMTUDISC_RPOBE").
Quoted source text, attributed separately from HOL analysis.