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CVE Record

CVE-2022-48839: net/packet: fix slab-out-of-bounds access in packet_recvmsg()

In the Linux kernel, the following vulnerability has been resolved: net/packet: fix slab-out-of-bounds access in packet_recvmsg() syzbot found that when an AF_PACKET socket is using PACKET_COPY_THRESH and mmap operations, tpacket_rcv() is queueing skbs with garbage in skb->cb[], triggering a too big copy [1] Presumably, users of af_packet using mmap() already gets correct metadata from the mapped buffer, we can simply make sure to clear 12 bytes that might be copied to user space later. BUG: KASAN: stack-out-of-bounds in memcpy include/linux/fortify-string.h:225 [inline] BUG: KASAN: stack-out-of-bounds in packet_recvmsg+0x56c/0x1150 net/packet/af_packet.c:3489 Write of size 165 at addr ffffc9000385fb78 by task syz-executor233/3631 CPU: 0 PID: 3631 Comm: syz-executor233 Not tainted 5.17.0-rc7-syzkaller-02396-g0b3660695e80 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xf/0x336 mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 memcpy+0x39/0x60 mm/kasan/shadow.c:66 memcpy include/linux/fortify-string.h:225 [inline] packet_recvmsg+0x56c/0x1150 net/packet/af_packet.c:3489 sock_recvmsg_nosec net/socket.c:948 [inline] sock_recvmsg net/socket.c:966 [inline] sock_recvmsg net/socket.c:962 [inline] ____sys_recvmsg+0x2c4/0x600 net/socket.c:2632 ___sys_recvmsg+0x127/0x200 net/socket.c:2674 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fdfd5954c29 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcf8e71e48 EFLAGS: 00000246 ORIG_RAX: 000000000000002f RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fdfd5954c29 RDX: 0000000000000000 RSI: 0000000020000500 RDI: 0000000000000005 RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcf8e71e60 R13: 00000000000f4240 R14: 000000000000c1ff R15: 00007ffcf8e71e54 </TASK> addr ffffc9000385fb78 is located in stack of task syz-executor233/3631 at offset 32 in frame: ____sys_recvmsg+0x0/0x600 include/linux/uio.h:246 this frame has 1 object: [32, 160) 'addr' Memory state around the buggy address: ffffc9000385fa80: 00 04 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 ffffc9000385fb00: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 >ffffc9000385fb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f3 ^ ffffc9000385fc00: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 f1 ffffc9000385fc80: f1 f1 f1 00 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 ==================================================================

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-48839 is a Linux kernel bug in AF_PACKET socket handling. Under a specific packet socket configuration, the kernel can copy too much data because internal metadata is not cleared correctly. The provided sources show this was found by syzbot and fixed in upstream stable kernel commits; they do not show active exploitation.

Executive priority

Handle through normal kernel patch management with elevated attention for multi-user, container, or untrusted workload environments. No source provided here supports emergency treatment based on active exploitation.

Technical view

The flaw is in net/packet packet_recvmsg(). When AF_PACKET uses PACKET_COPY_THRESH with mmap operations, tpacket_rcv() can queue skbs with uninitialized skb->cb[] contents, leading packet_recvmsg() to perform an oversized memcpy and trigger KASAN out-of-bounds reports. The fix clears the relevant 12 bytes before later user-space copying.

Likely exposure

Exposure is most likely on Linux systems running affected kernel versions where local code can exercise AF_PACKET sockets with PACKET_COPY_THRESH and mmap. The bundle lists Linux as affected but does not provide distribution package mappings or a CVSS score.

Exploitation context

The source bundle cites syzbot/KASAN evidence and kernel stable fixes. It does not cite CISA KEV listing, public exploitation, or in-the-wild attacks. Treat exploitability details as incomplete rather than confirmed.

Researcher notes

The description supports an out-of-bounds memory access in packet_recvmsg() caused by stale skb->cb[] metadata. The exact impact beyond KASAN-detected memory corruption is not fully characterized in the provided sources, and no CVSS or CWE is supplied.

Mitigation direction

  • Apply kernel updates containing the referenced stable fixes.
  • Check Linux distribution advisories for package-specific fixed versions.
  • Prioritize shared hosts and systems running untrusted local workloads.
  • Avoid direct wrangler or deploy implications; this is kernel-level remediation.
  • Track vendor guidance if kernel package mapping is unclear.

Validation and detection

  • Inventory Linux kernel versions across affected assets.
  • Compare installed kernels with distribution fixed-version advisories.
  • Confirm AF_PACKET exposure assumptions for untrusted local users or workloads.
  • Verify patched systems include the relevant stable kernel fix.
  • Record exceptions where vendor guidance is still pending.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2022-48839 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1f, 0fb375fb9b93b7d822debc6a734052337ccfdb1funaffected
LinuxLinux2.6.14, 0, 4.9.308, 4.14.273, 4.19.236, 5.4.187, 5.10.108, 5.15.31, 5.16.17, 5.17affected
Weakness

CWE details

No CWE listed

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