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CVE-2026-64554· NVD / CVE Program· CNA Linux

netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.25% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 00c06ef8c018493943891a7d0ca82b71b24f3180, 1c4f67c89fd27c4df4c70b135c2c59627698b3c0, 2731efa6364e47934c96eb69e01ea131e8af8030.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 00c06ef8c018493943891a7d0ca82b71b24f3180, 1c4f67c89fd27c4df4c70b135c2c59627698b3c0, 2731efa6364e47934c96eb69e01ea131e8af8030 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: netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment() br_ip6_fragment() gets prevhdr, a pointer into the skb head, from ip6_find_1stfragopt(), then calls skb_checksum_help(). For a cloned skb skb_checksum_help() reallocates the head via pskb_expand_head(), leaving prevhdr dangling. It is later dereferenced in ip6_frag_next(), causing a use-after-free write. Save prevhdr's offset before skb_checksum_help() and recompute it after, like commit ef0efcd3bd3f ("ipv6: Fix dangling pointer when ipv6 fragment"). BUG: KASAN: slab-use-after-free in ip6_frag_next (net/ipv6/ip6_output.c:857) Write of size 1 at addr ffff888013ff5016 by task exploit/141 Call Trace: ... kasan_report (mm/kasan/report.c:595) ip6_frag_next (net/ipv6/ip6_output.c:857) br_ip6_fragment (net/ipv6/netfilter.c:212) nf_ct_bridge_post (net/bridge/netfilter/nf_conntrack_bridge.c:407) nf_hook_slow (net/netfilter/core.c:619) br_forward_finish (net/bridge/br_forward.c:66) __br_forward (net/bridge/br_forward.c:115) maybe_deliver (net/bridge/br_forward.c:191) br_flood (net/bridge/br_forward.c:245) br_handle_frame_finish (net/bridge/br_input.c:229) br_handle_frame (net/bridge/br_input.c:442) ... packet_sendmsg (net/packet/af_packet.c:3114) ... do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Jul 27, 2026
Updated
Aug 17, 2026
EPSS
0.3% · 16th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CNA vs NVD score

NVD
—
CNA · Linux
8.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • 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 you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

—

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

    • 5.3affected
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 8c10778ec674b67a07ea042fcba64270f3f38a5aaffected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 2731efa6364e47934c96eb69e01ea131e8af8030affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 00c06ef8c018493943891a7d0ca82b71b24f3180affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before c141f69d0a0fb16964dbc293650047e69bda8af7affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before f2e6596d10783557aeb9668da2a3b4d19deb2001affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 1c4f67c89fd27c4df4c70b135c2c59627698b3c0affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 4ac981a8b7ce7aec99a52d08f8a8953e8e120067affected · git
    • 764dd163ac922f8683b5bcd3007251ce7b26cd33 and later · before 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643daffected · git
    • before 5.3not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

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 Linux00c06ef8c018493943891a7d0ca82b71b24f3180Vendor (CNA)
Linux Linux1c4f67c89fd27c4df4c70b135c2c59627698b3c0Vendor (CNA)
Linux Linux2731efa6364e47934c96eb69e01ea131e8af8030Vendor (CNA)
Linux Linux4ac981a8b7ce7aec99a52d08f8a8953e8e120067Vendor (CNA)
Linux Linux86f3ce81dd2b4b0aa2c3016c989a943e4b1b643dVendor (CNA)
Linux Linux8c10778ec674b67a07ea042fcba64270f3f38a5aVendor (CNA)
Linux Linuxc141f69d0a0fb16964dbc293650047e69bda8af7Vendor (CNA)
Linux Linuxf2e6596d10783557aeb9668da2a3b4d19deb2001Vendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

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. Fix✗ → ✓

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

References

Show all references (7 more)

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

All records