{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-31415 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-31415 is a medium-severity vulnerability in Linux kernel, published on 13 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-31415 and fix it if it is affected.\n\nWhat it is: CVE-2026-31415 is a medium-severity vulnerability in Linux kernel, published on 13 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-31415 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-31415/ (Markdown: https://insights.sbomify.com/CVE-2026-31415/index.md)","id":"CVE-2026-31415","markdown":"https://insights.sbomify.com/CVE-2026-31415/index.md","name":"CVE-2026-31415","record":{"aliases":["BELL-CVE-2026-31415","DEBIAN-CVE-2026-31415","GHSA-2rf4-5672-vqwm","ROOT-OS-DEBIAN-11-CVE-2026-31415","ROOT-OS-DEBIAN-12-CVE-2026-31415","ROOT-OS-DEBIAN-13-CVE-2026-31415","ROOT-OS-UBUNTU-2204-CVE-2026-31415","ROOT-OS-UBUNTU-2404-CVE-2026-31415","UBUNTU-CVE-2026-31415"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel IPv6","requires_auth":"low_privilege","summary":"A local attacker can trigger a kernel panic via integer overflow in IPv6 sendmsg handling, causing denial of service.","user_interaction":"not_required","vuln_class":"integer_overflow"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-617","name":"Reachable Assertion"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid overflows in ip6_datagram_send_ctl()\n\nYiming Qian reported :\n\u003cquote\u003e\n I believe I found a locally triggerable kernel bug in the IPv6 sendmsg\n ancillary-data path that can panic the kernel via `skb_under_panic()`\n (local DoS).\n\n The core issue is a mismatch between:\n\n - a 16-bit length accumulator (`struct ipv6_txoptions::opt_flen`, type\n `__u16`) and\n - a pointer to the *last* provided destination-options header (`opt-\u003edst1opt`)\n\n when multiple `IPV6_DSTOPTS` control messages (cmsgs) are provided.\n\n - `include/net/ipv6.h`:\n   - `struct ipv6_txoptions::opt_flen` is `__u16` (wrap possible).\n (lines 291-307, especially 298)\n - `net/ipv6/datagram.c:ip6_datagram_send_ctl()`:\n   - Accepts repeated `IPV6_DSTOPTS` and accumulates into `opt_flen`\n without rejecting duplicates. (lines 909-933)\n - `net/ipv6/ip6_output.c:__ip6_append_data()`:\n   - Uses `opt-\u003eopt_flen + opt-\u003eopt_nflen` to compute header\n sizes/headroom decisions. (lines 1448-1466, especially 1463-1465)\n - `net/ipv6/ip6_output.c:__ip6_make_skb()`:\n   - Calls `ipv6_push_frag_opts()` if `opt-\u003eopt_flen` is non-zero.\n (lines 1930-1934)\n - `net/ipv6/exthdrs.c:ipv6_push_frag_opts()` / `ipv6_push_exthdr()`:\n   - Push size comes from `ipv6_optlen(opt-\u003edst1opt)` (based on the\n pointed-to header). (lines 1179-1185 and 1206-1211)\n\n 1. `opt_flen` is a 16-bit accumulator:\n\n - `include/net/ipv6.h:298` defines `__u16 opt_flen; /* after fragment hdr */`.\n\n 2. `ip6_datagram_send_ctl()` accepts *repeated* `IPV6_DSTOPTS` cmsgs\n and increments `opt_flen` each time:\n\n - In `net/ipv6/datagram.c:909-933`, for `IPV6_DSTOPTS`:\n   - It computes `len = ((hdr-\u003ehdrlen + 1) \u003c\u003c 3);`\n   - It checks `CAP_NET_RAW` using `ns_capable(net-\u003euser_ns,\n CAP_NET_RAW)`. (line 922)\n   - Then it does:\n     - `opt-\u003eopt_flen += len;` (line 927)\n     - `opt-\u003edst1opt = hdr;` (line 928)\n\n There is no duplicate rejection here (unlike the legacy\n `IPV6_2292DSTOPTS` path which rejects duplicates at\n `net/ipv6/datagram.c:901-904`).\n\n If enough large `IPV6_DSTOPTS` cmsgs are provided, `opt_flen` wraps\n while `dst1opt` still points to a large (2048-byte)\n destination-options header.\n\n In the attached PoC (`poc.c`):\n\n - 32 cmsgs with `hdrlen=255` =\u003e `len = (255+1)*8 = 2048`\n - 1 cmsg with `hdrlen=0` =\u003e `len = 8`\n - Total increment: `32*2048 + 8 = 65544`, so `(__u16)opt_flen == 8`\n - The last cmsg is 2048 bytes, so `dst1opt` points to a 2048-byte header.\n\n 3. The transmit path sizes headers using the wrapped `opt_flen`:\n\n- In `net/ipv6/ip6_output.c:1463-1465`:\n  - `headersize = sizeof(struct ipv6hdr) + (opt ? opt-\u003eopt_flen +\n opt-\u003eopt_nflen : 0) + ...;`\n\n With wrapped `opt_flen`, `headersize`/headroom decisions underestimate\n what will be pushed later.\n\n 4. When building the final skb, the actual push length comes from\n `dst1opt` and is not limited by wrapped `opt_flen`:\n\n - In `net/ipv6/ip6_output.c:1930-1934`:\n   - `if (opt-\u003eopt_flen) proto = ipv6_push_frag_opts(skb, opt, proto);`\n - In `net/ipv6/exthdrs.c:1206-1211`, `ipv6_push_frag_opts()` pushes\n `dst1opt` via `ipv6_push_exthdr()`.\n - In `net/ipv6/exthdrs.c:1179-1184`, `ipv6_push_exthdr()` does:\n   - `skb_push(skb, ipv6_optlen(opt));`\n   - `memcpy(h, opt, ipv6_optlen(opt));`\n\n With insufficient headroom, `skb_push()` underflows and triggers\n `skb_under_panic()` -\u003e `BUG()`:\n\n - `net/core/skbuff.c:2669-2675` (`skb_push()` calls `skb_under_panic()`)\n - `net/core/skbuff.c:207-214` (`skb_panic()` ends in `BUG()`)\n\n - The `IPV6_DSTOPTS` cmsg path requires `CAP_NET_RAW` in the target\n netns user namespace (`ns_capable(net-\u003euser_ns, CAP_NET_RAW)`).\n - Root (or any task with `CAP_NET_RAW`) can trigger this without user\n namespaces.\n - An unprivileged `uid=1000` user can trigger this if unprivileged\n user namespaces are enabled and it can create a userns+netns to obtain\n namespaced `CAP_NET_RAW` (the attached PoC does this).\n\n - Local denial of service: kernel BUG/panic (system crash).\n -\n---truncated---","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"ipv6: avoid overflows in ip6_datagram_send_ctl()","id":"CVE-2026-31415","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"integer_overflow","year":"2026"},"n_packages":0,"n_references":8,"next":{"headline":"netfilter: nfnetlink_log: account for netlink header size","id":"CVE-2026-31416"},"packages":[],"prev":{"headline":"netfilter: nf_conntrack_expect: use expect-\u003ehelper","id":"CVE-2026-31414"},"products":["Linux"],"published":"2026-04-13","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-10-15","vendors":["Linux"]},"summary":"A local attacker can trigger a kernel panic via integer overflow in IPv6 sendmsg handling, causing denial of service.","url":"https://insights.sbomify.com/CVE-2026-31415/"}