CVE-2026-64538

UNRATEDCVSS · not yet scored
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS v2: —Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().

fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled.

Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad ("ipv6: Fix null-ptr-deref in fib6_mtu().").

Oops: general protection fault, ... KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af] RIP: 0010:fib6_nh_mtu_change+0x203/0x990 rt6_mtu_change_route+0x141/0x1d0 __fib6_clean_all+0xd0/0x160 rt6_mtu_change+0xb4/0x100 ndisc_router_discovery+0x24b5/0x2cb0 icmpv6_rcv+0x12e9/0x1710 ipv6_rcv+0x39b/0x410

CVSS v3
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
0%
EPSS %ILE
7%
KEV
Not listed

Published

July 27, 2026

Last Modified

August 17, 2026

References (8)

Vendor Advisories for CVE-2026-64538(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(6 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (55 versions)5.10.262-1—
linux-6.16.1.106-3~deb11u1 ... 6.1.177-1~deb11u1 (22 versions)6.1.180-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (55 versions)6.1.180-1—
linux-6.12—6.12.100-1~deb12u1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.96-1 (31 versions)6.12.100-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (157 versions)7.1.5-1—

Data Freshness Timeline

(refreshed 6× in last 7d / 38× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 23:49 UTCGHSA enrichment
  3. 2026-08-28 21:42 UTCEPSS rescore
  4. 2026-08-26 14:47 UTCEPSS rescore
  5. 2026-08-25 13:49 UTCEPSS rescore
  6. 2026-08-25 12:27 UTCGHSA enrichment
  7. 2026-08-23 00:19 UTCEPSS rescore
  8. 2026-08-22 18:10 UTCGHSA enrichment
  9. 2026-08-21 23:49 UTCEPSS rescore
  10. 2026-08-20 22:55 UTCEPSS rescore
  11. 2026-08-19 23:56 UTCGHSA enrichment
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-18 13:48 UTCEPSS rescore
  14. 2026-08-17 13:47 UTCEPSS rescore
  15. 2026-08-17 05:42 UTCGHSA enrichment
  16. 2026-08-17 05:25 UTCNVD update
  17. 2026-08-17 05:14 UTCGHSA enrichment
  18. 2026-08-17 05:05 UTCMITRE cvelistV5
  19. 2026-08-16 14:56 UTCEPSS rescore
  20. 2026-08-16 05:11 UTCGHSA enrichment
  21. 2026-08-15 01:30 UTCEPSS rescore
  22. 2026-08-13 22:00 UTCEPSS rescore
  23. 2026-08-13 10:58 UTCGHSA enrichment
  24. 2026-08-12 13:51 UTCEPSS rescore
  25. 2026-08-11 00:00 UTCEPSS rescore
Show 23 more
  1. 2026-08-10 16:45 UTCGHSA enrichment
  2. 2026-08-09 13:47 UTCEPSS rescore
  3. 2026-08-08 16:37 UTCEPSS rescore
  4. 2026-08-07 22:32 UTCGHSA enrichment
  5. 2026-08-06 13:47 UTCEPSS rescore
  6. 2026-08-05 19:17 UTCEPSS rescore
  7. 2026-08-05 19:17 UTCEPSS rescore
  8. 2026-08-05 04:19 UTCGHSA enrichment
  9. 2026-08-04 15:10 UTCEPSS rescore
  10. 2026-08-04 10:39 UTCEPSS rescore
  11. 2026-08-03 10:36 UTCEPSS rescore
  12. 2026-08-02 10:03 UTCGHSA enrichment
  13. 2026-08-02 02:27 UTCEPSS rescore
  14. 2026-07-30 16:28 UTCEPSS rescore
  15. 2026-07-30 15:50 UTCEG score recompute
  16. 2026-07-30 15:50 UTCGHSA enrichment
  17. 2026-07-30 01:30 UTCEPSS rescore
  18. 2026-07-30 01:30 UTCEPSS rescore
  19. 2026-07-28 15:37 UTCEPSS rescore
  20. 2026-07-27 21:35 UTCGHSA enrichment
  21. 2026-07-27 21:19 UTCNVD update
  22. 2026-07-27 20:34 UTCEG score recompute
  23. 2026-07-27 20:24 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-64538?
CVE-2026-64538 is a publicly disclosed vulnerability published on July 27, 2026. In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix null-ptr-deref in fib6nhmtu_change(). fib6nhmtuchange() re-fetches idev via in6dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6ptr with RCUINITPOINTER() after…
When was CVE-2026-64538 disclosed?
CVE-2026-64538 was first published in the National Vulnerability Database on July 27, 2026, with the most recent update on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64538 actively exploited?
CVE-2026-64538 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 92.7% of all scored CVEs.
How do I remediate CVE-2026-64538?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64538, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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