Linux KernelOperating system · Linux

CVE-2022-49330

MEDIUM · 5.5 CVSS v3.1 Published 2025-02-26

Fix available

A fix is available. Upgrade to 4.9.318 / 4.14.283 or later.

See remediation →

57/100

Remediation priority · Elevated

Zero-click Patch available

Official description

NVD · unedited

In the Linux kernel, the following vulnerability has been resolved: tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd syzbot got a new report [1] finally pointing to a very old bug, added in initial support for MTU probing. tcp_mtu_probe() has checks about starting an MTU probe if tcp_snd_cwnd(tp) >= 11. But nothing prevents tcp_snd_cwnd(tp) to be reduced later and before the MTU probe succeeds. This bug would lead to potential zero-divides. Debugging added in commit 40570375356c ("tcp: add accessors to read/set tp->snd_cwnd") has paid off :) While we are at it, address potential overflows in this code. [1] WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Modules linked in: CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline] RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287 RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000 RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520 R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50 R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000 FS: 00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476 sk_backlog_rcv include/net/sock.h:1061 [inline] __release_sock+0x1d8/0x4c0 net/core/sock.c:2849 release_sock+0x5d/0x1c0 net/core/sock.c:3404 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] __sys_sendto+0x439/0x5c0 net/socket.c:2119 __do_sys_sendto net/socket.c:2131 [inline] __se_sys_sendto net/socket.c:2127 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2127 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f6431289109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109 RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000

Technical summary

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions

NVD · CPE data

Linux KernelOperating system

Affected:>= 2.6.17, < 4.9.318>= 4.10, < 4.14.283>= 4.15, < 4.19.247>= 4.20, < 5.4.198>= 5.5, < 5.10.122>= 5.11, < 5.15.47>= 5.16, < 5.17.15>= 5.18, < 5.18.4

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation

dbcve · scoped

Upgrade available Upgrade to 4.9.318 / 4.14.283 / 4.19.247 or later

Fixed in 4.9.3184.14.2834.19.247

Vendor patch git.kernel.org →

Recommended fix High confidence

Upgrade to kernel >= 4.9.318 (if on 4.9.x), >= 4.14.283 (if on 4.14.x), >= 4.19.247 (if on 4.19.x), or >= 5.4.198 (if on 5.4.x). For older branches (2.6.17 to 4.9), upgrade to 4.9.318 or migrate to a supported stable branch.

1. Identify the current running kernel version using `uname -r`
2. Determine which stable kernel branch your current version belongs to based on the affected ranges (4.9.x, 4.14.x, 4.19.x, or 5.4.x)
3. Upgrade the Linux kernel to the first fixed version in your branch: for 4.9.x upgrade to >=4.9.318, for 4.14.x upgrade to >=4.14.283, for 4.19.x upgrade to >=4.19.247, or for 5.4.x upgrade to >=5.4.198
4. On Debian/Ubuntu: `apt-get update && apt-get dist-upgrade` or install specific kernel package
5. On RHEL/CentOS: `yum update kernel`
6. On Alpine: `apk add linux-lts` (or appropriate LTS kernel)
7. After upgrade, reboot the system to load the new kernel: `reboot`
8. Verify the fix is applied by checking the kernel version and confirming tcp_mtup_probe_success includes the snd_cwnd check: `grep -A20 'tcp_mtup_probe_success' /proc/kallsyms` (if available) or by checking the source if you compile your own kernel

Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with proprietary kernel modules or older drivers. Ensure backups and test in staging if possible.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-49330 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2022-49330?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsUpgrade to 4.9.318 / 4.14.283 or later

Severity 5.5 Medium

Exploit likelihood EPSS, next 30 days 0.8%

Affects: Linux Kernel

Remediation

Need this fixed?

Get a fix

Estimated effortfrom ~9 hrs

ComplexityModerate

Typical engagementfrom $1,600

What a fix involves

We scope it with you and confirm a fixed quote
A specialist builds a reviewed fix
You deploy it to staging first
Optional re-test once it’s live

We specialise in CVE remediation. Send your environment and we’ll scope CVE-2022-49330 and return a fixed quote.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Remediation

References