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NVD / CVE Program· CNA Linux

CVE-2026-23277: net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4, 0cc0c2e661af418bbf7074179ea5cfffc0a5c466, 21ea283c2750c8307aa35ee832b0951cc993c27d; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1.

Low priority for now. Upgrade to Linux Linux 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4, 0cc0c2e661af418bbf7074179ea5cfffc0a5c466, 21ea283c2750c8307aa35ee832b0951cc993c27d; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit teql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit through slave devices, but does not update skb->dev to the slave device beforehand. When a gretap tunnel is a TEQL slave, the transmit path reaches iptunnel_xmit() which saves dev = skb->dev (still pointing to teql0 master) and later calls iptunnel_xmit_stats(dev, pkt_len). This function does: get_cpu_ptr(dev->tstats) Since teql_master_setup() does not set dev->pcpu_stat_type to NETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats for teql0, so dev->tstats is NULL. get_cpu_ptr(NULL) computes NULL + __per_cpu_offset[cpu], resulting in a page fault. BUG: unable to handle page fault for address: ffff8880e6659018 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 68bc067 P4D 68bc067 PUD 0 Oops: Oops: 0002 [#1] SMP KASAN PTI RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89) Call Trace: <TASK> ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847) __gre_xmit (net/ipv4/ip_gre.c:478) gre_tap_xmit (net/ipv4/ip_gre.c:779) teql_master_xmit (net/sched/sch_teql.c:319) dev_hard_start_xmit (net/core/dev.c:3887) sch_direct_xmit (net/sched/sch_generic.c:347) __dev_queue_xmit (net/core/dev.c:4802) neigh_direct_output (net/core/neighbour.c:1660) ip_finish_output2 (net/ipv4/ip_output.c:237) __ip_finish_output.part.0 (net/ipv4/ip_output.c:315) ip_mc_output (net/ipv4/ip_output.c:369) ip_send_skb (net/ipv4/ip_output.c:1508) udp_send_skb (net/ipv4/udp.c:1195) udp_sendmsg (net/ipv4/udp.c:1485) inet_sendmsg (net/ipv4/af_inet.c:859) __sys_sendto (net/socket.c:2206) Fix this by setting skb->dev = slave before calling netdev_start_xmit(), so that tunnel xmit functions see the correct slave device with properly allocated tstats.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Mar 20, 2026
Updated
Nov 5, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel4.5 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.167
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.78
  • linux linux kernel6.13 and later · before 6.18.19
  • linux linux kernel6.19 and later · before 6.19.9
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 4.5affected
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 383493b9940e3d1b5517424081b3e072e20ec43caffected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 6b1f563d670162e188a0f2aec39c24b67b106e17affected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 57c153249143333bbf4ecf927bdf8aa2696ee397affected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 59b06d8b9bdb6b64b3c534c18da68bce5ccd31beaffected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 81a43e8005366f16e629d8c95dfe05beaa8d36a7affected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4affected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 21ea283c2750c8307aa35ee832b0951cc993c27daffected · git
    • 039f50629b7f860f36644ed1f34b27da9aa62f43 and later · before 0cc0c2e661af418bbf7074179ea5cfffc0a5c466affected · git
    • before 4.5not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.10-16.19.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-23275Mar 20, 2026 · io_uring: ensure ctx->rings is stable for task work flags manipulation
    31Monitor
  • ← EarlierCVE-2026-23276Mar 20, 2026 · net: add xmit recursion limit to tunnel xmit functions
    22Monitor
  • Later →CVE-2026-23278Mar 20, 2026 · netfilter: nf_tables: always walk all pending catchall elements
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0bad9c86edd22dec4df83c2b29872d66fd8a2ff4Vendor (CNA)
Linux Linux0cc0c2e661af418bbf7074179ea5cfffc0a5c466Vendor (CNA)
Linux Linux21ea283c2750c8307aa35ee832b0951cc993c27dVendor (CNA)
Linux Linux383493b9940e3d1b5517424081b3e072e20ec43cVendor (CNA)
Linux Linux57c153249143333bbf4ecf927bdf8aa2696ee397Vendor (CNA)
Linux Linux59b06d8b9bdb6b64b3c534c18da68bce5ccd31beVendor (CNA)
Linux Linux6b1f563d670162e188a0f2aec39c24b67b106e17Vendor (CNA)
Linux Linux81a43e8005366f16e629d8c95dfe05beaa8d36a7Vendor (CNA)
azl3 kernel 6.6.126.1-1 on Azure Linux 3.06.6.130.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records