{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-63825 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-63825 is a critical vulnerability in Linux, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-63825 and fix it if it is affected.\n\nWhat it is: CVE-2026-63825 is a critical vulnerability in Linux, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-63825 in the wild and no public exploit code.\n\nAffected product: Linux. 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-2026-63825/ (Markdown: https://insights.sbomify.com/CVE-2026-63825/index.md)","id":"CVE-2026-63825","markdown":"https://insights.sbomify.com/CVE-2026-63825/index.md","name":"CVE-2026-63825","record":{"aliases":["AZL-92516","BELL-CVE-2026-63825","DEBIAN-CVE-2026-63825","GHSA-xc4c-7263-hq9r","ROOT-OS-DEBIAN-11-CVE-2026-63825","ROOT-OS-DEBIAN-12-CVE-2026-63825","ROOT-OS-DEBIAN-13-CVE-2026-63825","ROOT-OS-UBUNTU-2204-CVE-2026-63825","UBUNTU-CVE-2026-63825"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service","code_execution"],"network_reachable":"yes","non_default_config":true,"product_category":"Linux kernel","requires_auth":"none","summary":"Concurrent GCOV counter updates in the Linux kernel can cause out-of-bounds writes and crashes during IPComp processing, requiring atomic counter updates.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":9.8,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\ngcov: use atomic counter updates to fix concurrent access crashes\n\nGCC's GCOV instrumentation can merge global branch counters with loop\ninduction variables as an optimization.  In inflate_fast(), the inner copy\nloops get transformed so that the GCOV counter value is loaded multiple\ntimes to compute the loop base address, start index, and end bound.  Since\nGCOV counters are global (not per-CPU), concurrent execution on different\nCPUs causes the counter to change between loads, producing inconsistent\nvalues and out-of-bounds memory writes.\n\nThe crash manifests during IPComp (IP Payload Compression) processing when\ninflate_fast() runs concurrently on multiple CPUs:\n\n  BUG: unable to handle page fault for address: ffffd0a3c0902ffa\n  RIP: inflate_fast+1431\n  Call Trace:\n   zlib_inflate\n   __deflate_decompress\n   crypto_comp_decompress\n   ipcomp_decompress [xfrm_ipcomp]\n   ipcomp_input [xfrm_ipcomp]\n   xfrm_input\n\nAt the crash point, the compiler generated three loads from the same\nglobal GCOV counter (__gcov0.inflate_fast+216) to compute base, start, and\nend for an indexed loop.  Another CPU modified the counter between loads,\nmaking the values inconsistent - the write went 3.4 MB past a 65 KB\nbuffer.\n\nAdd -fprofile-update=prefer-atomic to CFLAGS_GCOV at the global level in\nthe top-level Makefile, guarded by a try-run compile test.  The test\ncompiles a minimal program with and without -fprofile-update=prefer-atomic\nusing the full KBUILD_CFLAGS, then compares undefined symbols in the\nresulting object files.  If prefer-atomic introduces new undefined\nreferences (such as __atomic_fetch_add_8 on i386 or __aarch64_ldadd8_relax\non arm64 with outline-atomics), the flag is not added -- the kernel does\nnot link against libatomic.\n\nOn architectures where GCC inlines 64-bit atomic counter updates (x86_64,\ns390, ...) the test passes and the flag is enabled, preventing the\ncompiler from merging counters with loop induction variables and fixing\nthe observed concurrent-access crash.\n\nOn architectures where the flag would introduce libatomic dependencies, it\nis silently omitted and behaviour is no worse than before this patch.\n\nMove the CFLAGS_GCOV block from its original position (before the arch\nMakefile include) to after the core KBUILD_CFLAGS assignments but before\nthe scripts/Makefile.gcc-plugins include.  This placement ensures the\ntry-run test sees arch-specific flags (-m32, -march=,\n-mno-outline-atomics) while avoiding GCC plugin flags (-fplugin=) that\nwould break the test on clean builds when plugin shared objects do not yet\nexist.","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":"gcov: use atomic counter updates to fix concurrent access crashes","id":"CVE-2026-63825","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"race_condition","year":"2026"},"n_packages":0,"n_references":5,"next":{"headline":"fbdev: fix use-after-free in store_modes()","id":"CVE-2026-63826"},"packages":[],"prev":{"headline":"KEYS: fix overflow in keyctl_pkey_params_get_2()","id":"CVE-2026-63824"},"products":["Linux"],"published":"2026-07-19","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-10-21","vendors":["Linux"]},"summary":"Concurrent GCOV counter updates in the Linux kernel can cause out-of-bounds writes and crashes during IPComp processing, requiring atomic counter updates.","url":"https://insights.sbomify.com/CVE-2026-63825/"}