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CVE Record

CVE-2024-26815: net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check

In the Linux kernel, the following vulnerability has been resolved: net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check taprio_parse_tc_entry() is not correctly checking TCA_TAPRIO_TC_ENTRY_INDEX attribute: int tc; // Signed value tc = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_INDEX]); if (tc >= TC_QOPT_MAX_QUEUE) { NL_SET_ERR_MSG_MOD(extack, "TC entry index out of range"); return -ERANGE; } syzbot reported that it could fed arbitary negative values: UBSAN: shift-out-of-bounds in net/sched/sch_taprio.c:1722:18 shift exponent -2147418108 is negative CPU: 0 PID: 5066 Comm: syz-executor367 Not tainted 6.8.0-rc7-syzkaller-00136-gc8a5c731fd12 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_shift_out_of_bounds+0x3c7/0x420 lib/ubsan.c:386 taprio_parse_tc_entry net/sched/sch_taprio.c:1722 [inline] taprio_parse_tc_entries net/sched/sch_taprio.c:1768 [inline] taprio_change+0xb87/0x57d0 net/sched/sch_taprio.c:1877 taprio_init+0x9da/0xc80 net/sched/sch_taprio.c:2134 qdisc_create+0x9d4/0x1190 net/sched/sch_api.c:1355 tc_modify_qdisc+0xa26/0x1e40 net/sched/sch_api.c:1776 rtnetlink_rcv_msg+0x885/0x1040 net/core/rtnetlink.c:6617 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7f1b2dea3759 Code: 48 83 c4 28 c3 e8 d7 19 00 00 0f 1f 80 00 00 00 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:00007ffd4de452f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f1b2def0390 RCX: 00007f1b2dea3759 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 0000000000000003 R08: 0000555500000000 R09: 0000555500000000 R10: 0000555500000000 R11: 0000000000000246 R12: 00007ffd4de45340 R13: 00007ffd4de45310 R14: 0000000000000001 R15: 00007ffd4de45340

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A local user with limited privileges may be able to give Linux’s TAPRIO network scheduler an invalid index, causing an unsafe kernel operation. The supplied record rates this 7.8 High, but documents a sanitizer-detected kernel error rather than a proven system compromise.

Executive priority

Treat as a high-priority kernel maintenance issue on exposed multi-user or container platforms. It is less urgent on systems where untrusted local actors cannot administer traffic control. Do not interpret the High score as proof of active exploitation or demonstrated compromise.

Technical view

TCA_TAPRIO_TC_ENTRY_INDEX is read as an unsigned 32-bit value into a signed integer. Large values can become negative and bypass the upper-bound check, producing a negative shift exponent in sch_taprio.c. The referenced stable-kernel changes correct the index validation.

Likely exposure

Exposure is limited to Linux systems where a local actor can submit TAPRIO traffic-control configuration. The bundle names releases spanning 6.1 through 6.9, but its flattened version data does not clearly distinguish vulnerable and corrected cutoffs. Confirm status using distribution-specific kernel advisories and backport information.

Exploitation context

The supplied record is not listed as KEV and none of its cited sources claims active exploitation. The evidence is a syzbot-generated UBSAN shift-out-of-bounds report on a test kernel. It does not demonstrate privilege escalation, code execution, or real-world compromise.

Researcher notes

The report demonstrates undefined shift behavior after signed conversion, not an exploitation primitive. Researchers should compare the referenced stable patches with distribution backports and assess reachable privilege boundaries. The supplied CVSS asserts high confidentiality, integrity, and availability impact, but the narrative evidence does not independently demonstrate those outcomes.

Mitigation direction

  • Apply a vendor kernel update incorporating the referenced upstream validation fix.
  • Reboot affected systems into the corrected kernel after installation.
  • If patching is delayed, consult vendor guidance and restrict untrusted access to traffic-control administration.
  • Prioritize multi-user and container hosts where local actors can administer network scheduling.

Validation and detection

  • Inventory running kernel and distribution build versions across Linux systems.
  • Map each distribution build to vendor advisories or documented backports for this CVE.
  • Confirm the running kernel contains a referenced stable fix or vendor-equivalent patch.
  • Verify systems booted the corrected kernel after maintenance.
  • Review which local users and containers can modify TAPRIO traffic-control settings.
Prepared
Confidence
medium
Sources
7

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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ATT&CK lookup starting points

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CVE-2024-26815 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
3Timeline events
2ADP providers
6Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-26815Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
LinuxLinuxa54fc09e4cba3004443aa05979f8c678196c8226, a54fc09e4cba3004443aa05979f8c678196c8226, a54fc09e4cba3004443aa05979f8c678196c8226, a54fc09e4cba3004443aa05979f8c678196c8226, a54fc09e4cba3004443aa05979f8c678196c8226unaffected
LinuxLinux6.1, 0, 6.1.83, 6.6.23, 6.7.11, 6.8.2, 6.9affected
Weakness

CWE details

No CWE listed

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