{"id":"CVE-2022-49325","state":"PUBLISHED","title":"tcp: add accessors to read/set tp->snd_cwnd","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: add accessors to read/set tp->snd_cwnd\n\nWe had various bugs over the years with code\nbreaking the assumption that tp->snd_cwnd is greater\nthan zero.\n\nLately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added\nin commit 8b8a321ff72c (\"tcp: fix zero cwnd in tcp_cwnd_reduction\")\ncan trigger, and without a repro we would have to spend\nconsiderable time finding the bug.\n\nInstead of complaining too late, we want to catch where\nand when tp->snd_cwnd is set to an illegal value.","publishedAt":"2025-02-26T02:10:48.158Z","updatedAt":"2026-08-05T08:54:43.711Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"3308676ec525901bf1656014003c443a60730a04","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"5aba0ad44fb4a7fb78c5076c313456de199a3c29","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"41e191fe72282e193a7744e2fc1786b23156c9e4","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"40570375356c874b1578e05c1dcc3ff7c1322dbe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcp.h","include/trace/events/tcp.h","net/core/filter.c","net/ipv4/tcp.c","net/ipv4/tcp_bbr.c","net/ipv4/tcp_bic.c","net/ipv4/tcp_cdg.c","net/ipv4/tcp_cong.c","net/ipv4/tcp_cubic.c","net/ipv4/tcp_dctcp.c","net/ipv4/tcp_highspeed.c","net/ipv4/tcp_htcp.c","net/ipv4/tcp_hybla.c","net/ipv4/tcp_illinois.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_lp.c","net/ipv4/tcp_metrics.c","net/ipv4/tcp_nv.c","net/ipv4/tcp_output.c","net/ipv4/tcp_rate.c","net/ipv4/tcp_scalable.c","net/ipv4/tcp_vegas.c","net/ipv4/tcp_veno.c","net/ipv4/tcp_westwood.c","net/ipv4/tcp_yeah.c","net/ipv6/tcp_ipv6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"5.15.47","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.17.15","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18.4","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcp.h","include/trace/events/tcp.h","net/core/filter.c","net/ipv4/tcp.c","net/ipv4/tcp_bbr.c","net/ipv4/tcp_bic.c","net/ipv4/tcp_cdg.c","net/ipv4/tcp_cong.c","net/ipv4/tcp_cubic.c","net/ipv4/tcp_dctcp.c","net/ipv4/tcp_highspeed.c","net/ipv4/tcp_htcp.c","net/ipv4/tcp_hybla.c","net/ipv4/tcp_illinois.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_lp.c","net/ipv4/tcp_metrics.c","net/ipv4/tcp_nv.c","net/ipv4/tcp_output.c","net/ipv4/tcp_rate.c","net/ipv4/tcp_scalable.c","net/ipv4/tcp_vegas.c","net/ipv4/tcp_veno.c","net/ipv4/tcp_westwood.c","net/ipv4/tcp_yeah.c","net/ipv6/tcp_ipv6.c"]}],"references":["https://git.kernel.org/stable/c/3308676ec525901bf1656014003c443a60730a04","https://git.kernel.org/stable/c/5aba0ad44fb4a7fb78c5076c313456de199a3c29","https://git.kernel.org/stable/c/41e191fe72282e193a7744e2fc1786b23156c9e4","https://git.kernel.org/stable/c/40570375356c874b1578e05c1dcc3ff7c1322dbe"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/49xxx/CVE-2022-49325.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-49325","state":"PUBLISHED","datePublished":"2025-02-26T02:10:48.158Z","dateUpdated":"2026-08-05T08:54:43.711Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-02-26T02:08:31.538Z"},"containers":{"cna":{"title":"tcp: add accessors to read/set tp->snd_cwnd","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: add accessors to read/set tp->snd_cwnd\n\nWe had various bugs over the years with code\nbreaking the assumption that tp->snd_cwnd is greater\nthan zero.\n\nLately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added\nin commit 8b8a321ff72c (\"tcp: fix zero cwnd in tcp_cwnd_reduction\")\ncan trigger, and without a repro we would have to spend\nconsiderable time finding the bug.\n\nInstead of complaining too late, we want to catch where\nand when tp->snd_cwnd is set to an illegal value."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"3308676ec525901bf1656014003c443a60730a04","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"5aba0ad44fb4a7fb78c5076c313456de199a3c29","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"41e191fe72282e193a7744e2fc1786b23156c9e4","versionType":"git"},{"version":"5d424d5a674f782d0659a3b66d951f412901faee","status":"affected","lessThan":"40570375356c874b1578e05c1dcc3ff7c1322dbe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcp.h","include/trace/events/tcp.h","net/core/filter.c","net/ipv4/tcp.c","net/ipv4/tcp_bbr.c","net/ipv4/tcp_bic.c","net/ipv4/tcp_cdg.c","net/ipv4/tcp_cong.c","net/ipv4/tcp_cubic.c","net/ipv4/tcp_dctcp.c","net/ipv4/tcp_highspeed.c","net/ipv4/tcp_htcp.c","net/ipv4/tcp_hybla.c","net/ipv4/tcp_illinois.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_lp.c","net/ipv4/tcp_metrics.c","net/ipv4/tcp_nv.c","net/ipv4/tcp_output.c","net/ipv4/tcp_rate.c","net/ipv4/tcp_scalable.c","net/ipv4/tcp_vegas.c","net/ipv4/tcp_veno.c","net/ipv4/tcp_westwood.c","net/ipv4/tcp_yeah.c","net/ipv6/tcp_ipv6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"5.15.47","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.17.15","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18.4","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/tcp.h","include/trace/events/tcp.h","net/core/filter.c","net/ipv4/tcp.c","net/ipv4/tcp_bbr.c","net/ipv4/tcp_bic.c","net/ipv4/tcp_cdg.c","net/ipv4/tcp_cong.c","net/ipv4/tcp_cubic.c","net/ipv4/tcp_dctcp.c","net/ipv4/tcp_highspeed.c","net/ipv4/tcp_htcp.c","net/ipv4/tcp_hybla.c","net/ipv4/tcp_illinois.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_lp.c","net/ipv4/tcp_metrics.c","net/ipv4/tcp_nv.c","net/ipv4/tcp_output.c","net/ipv4/tcp_rate.c","net/ipv4/tcp_scalable.c","net/ipv4/tcp_vegas.c","net/ipv4/tcp_veno.c","net/ipv4/tcp_westwood.c","net/ipv4/tcp_yeah.c","net/ipv6/tcp_ipv6.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3308676ec525901bf1656014003c443a60730a04"},{"url":"https://git.kernel.org/stable/c/5aba0ad44fb4a7fb78c5076c313456de199a3c29"},{"url":"https://git.kernel.org/stable/c/41e191fe72282e193a7744e2fc1786b23156c9e4"},{"url":"https://git.kernel.org/stable/c/40570375356c874b1578e05c1dcc3ff7c1322dbe"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - Zero snd_cwnd arises in TCP congestion/MTU-probe paths reached from tcp_rcv_established → tcp_ack → tcp_clean_rtx_queue while processing inbound ACKs, so a remote TCP peer triggers it via ordinary network packets.\nAC:L - A remote peer on a data-heavy connection can shrink cwnd (loss/ECN) and deliver the ACKs that enter cwnd-reduction or probe-success; those peer-side conditions are attacker-controlled, and MTU probing is enabled in realistic deployments.\nPR:N - Exploitation requires only exchanging TCP segments on an established connection to a listening service; no authentication or local privileges are needed.\nUI:N - No victim user action is required beyond an already-running TCP endpoint that sends data and processes peer ACKs.\nS:U - Impact stays within the host kernel TCP/congestion-control authority with no VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:N - The defect only allows snd_cwnd to become zero and trip assertions/divides; it does not corrupt memory or disclose kernel or user data.\nI:N - There is no write primitive, type confusion, or control-flow hijack—only an illegal congestion-window value leading to WARN/div0/BUG paths.\nA:H - Zero snd_cwnd triggers WARN_ON_ONCE(!prior_cwnd), BUG_ON(cwnd <= in_flight), and divide-by-zero in congestion control, causing kernel oops/panic and full host DoS."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:54:43.711Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.15.47"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.17.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.18.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.19"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}