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NVD / CVE Program· CNA Linux

CVE-2026-80603: netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read

Noroxi assessment

Priority: Monitor (action score 36/100)

  • 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: 0.59% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 2393f0bd7a467ad475598f3a5b9de27ca36e3037, 2b70f61f569bb29acb380e6f616a1bbdee15668f, 437e0a3854b3a44ec15afa9ab88ec215adf3a2fd.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 2393f0bd7a467ad475598f3a5b9de27ca36e3037, 2b70f61f569bb29acb380e6f616a1bbdee15668f, 437e0a3854b3a44ec15afa9ab88ec215adf3a2fd 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: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read parse_dcc() treats data_end as an inclusive end pointer, but its only caller passes data_limit = ib_ptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= data_end, so when no newline is present, *tmp is read at tmp == data_end, one byte beyond the region filled by skb_header_pointer(). irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is capped at MAX_SEARCH_SIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simple_strtoul will consume it and produce a wrong DCC IP or port in the conntrack expectation. The extra allocation byte is also a fragile guard: if the cap or allocation size changes, this becomes a real out-of-bounds read. Change the loop and its post-loop check to use strict less-than, consistent with the caller's exclusive-end convention. Update the function comment accordingly.

CriticalCVSS 9.1 · v3.1—No exploit Fix available
Published
Aug 28, 2026
Updated
Oct 16, 2026
EPSS
0.5% · 48th percentile
CWE
—

Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.1
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.

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-80603

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

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7eaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 437e0a3854b3a44ec15afa9ab88ec215adf3a2fdaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2b70f61f569bb29acb380e6f616a1bbdee15668faffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2393f0bd7a467ad475598f3a5b9de27ca36e3037affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before aff589556ed772cb1c0c2d7b4d91ec45c0c39416affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before eeef3b81f449560653662df2dde6f6fe247c5365affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88aaffected · git
    • before 2.6.12not 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: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

Published before and after this one in the same product

  • ← EarlierCVE-2026-80601Aug 28, 2026 · batman-adv: gw: acquire ethernet header only after skb realloc
    35Monitor
  • ← EarlierCVE-2026-80602Aug 28, 2026 · perf/x86/amd/lbr: Fix kernel address leakage
    0Monitor
  • Later →CVE-2026-80604Aug 28, 2026 · HID: core: Fix OOB read in hid_get_report for numbered reports
    35Monitor

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 Linux2393f0bd7a467ad475598f3a5b9de27ca36e3037Vendor (CNA)
Linux Linux2b70f61f569bb29acb380e6f616a1bbdee15668fVendor (CNA)
Linux Linux437e0a3854b3a44ec15afa9ab88ec215adf3a2fdVendor (CNA)
Linux Linux910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1Vendor (CNA)
Linux Linuxabb8c32b88ea3f46beb68c34fe9a3ac8ed664e7eVendor (CNA)
Linux Linuxaff589556ed772cb1c0c2d7b4d91ec45c0c39416Vendor (CNA)
Linux Linuxeeef3b81f449560653662df2dde6f6fe247c5365Vendor (CNA)
Linux Linuxef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88aVendor (CNA)
debian:linux6.1.180-1 · 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.

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

  • Anyone who can reach it over the internet 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
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

—

CVSS vector

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

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. SSVC exploitation— → none
  2. 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