NVD / CVE Program· CNA Linux

CVE-2026-98123: sctp: fix soft lockup from unpadded ASCONF-ACK parameter iteration

MediumCVSS 5.5 · v3.1—No exploit Fix available

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: 0.09% (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 2cb0b0b1ed69430bf73740377ea0a1c44c50db63, 3be02999ab9131a4b96eb1eda4ca48b1cea80f03, 4548d843e7b29f6d150d8caae4e64015fa226b0c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 2cb0b0b1ed69430bf73740377ea0a1c44c50db63, 3be02999ab9131a4b96eb1eda4ca48b1cea80f03, 4548d843e7b29f6d150d8caae4e64015fa226b0c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1 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: sctp: fix soft lockup from unpadded ASCONF-ACK parameter iteration sctp_verify_asconf() walks ASCONF-ACK parameters with sctp_walk_params(), which advances by SCTP_PAD4(length), while the consumer sctp_get_asconf_response() iterates the same parameters advancing by the raw length, without padding. A single odd-length parameter desynchronises the two walks and makes the consumer interpret attacker-controlled bytes at a misaligned offset. When those bytes yield a length of zero, the while loop over asconf_ack_len makes no progress, spinning forever in softirq context, and the watchdog reports a soft lockup. All reads stay within the received skb, so the lockup is a pure remote denial of service. A remote peer can trigger it with a crafted ASCONF-ACK on an ADD-IP enabled association with an outstanding ASCONF (RFC 5061 section 4.1.2 requires the chunk to be authenticated, but the predefined empty key id 0 allows the peer to compute the same association HMAC from publicly exchanged parameters, so the gate does not help). The SCTP_PARAM_ERR_CAUSE case of sctp_verify_asconf() also performs no length check, letting a parameter without a complete error header reach the consumer, which reads errhdr.cause past the end of the parameter, an out-of-bounds read. Reject SCTP_PARAM_ERR_CAUSE parameters shorter than sizeof(struct sctp_addip_param) + sizeof(struct sctp_errhdr) at the verifier, and advance the consumer iterator with the same padding rule as the verifier to keep the two walks in lockstep. The verifier change guarantees a complete error header in every ERR_CAUSE parameter the consumer can see, so the consumer's asconf_ack_len check is dropped and it returns err_param->cause directly. The consumer padding fix is still required because odd lengths remain valid for SCTP_PARAM_ERR_CAUSE per RFC 5061. The issue was found by ZeroHive, a vulnerability hunting agent at Tencent Yunding Lab.

Denial of service

EUVD-2026-86954

Published: Sep 25, 2026
Updated: Oct 22, 2026
EPSS: 0.0% · 0th percentile
CWE: CWE-667

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Action score

Monitor

Low priority for now.

CVSS: 22 / 40 · 5.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.0%

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Noroxi analysis

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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.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

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 ba54cad229977f4fae6355dbdaf117088414fdd0affected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7d8e7ab6a0665888beee91f7ad77ac805963c4fdaffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5fbc6a778d5fce7628821236972596acb18e1065affected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4548d843e7b29f6d150d8caae4e64015fa226b0caffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before abf59d7f6fff23227256e8199aca5ade45758f8baffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3be02999ab9131a4b96eb1eda4ca48b1cea80f03affected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7ba84e2971d208a2d6413a334ec28a8a32cdce0faffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2cb0b0b1ed69430bf73740377ea0a1c44c50db63affected · git
- before 2.6.12not affected · semver

Affected versions · NVD (9)

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

linux linux kernel2.6.12.1 and later · before 5.10.271
linux linux kernel5.11 and later · before 5.15.222
linux linux kernel5.16 and later · before 6.1.189
linux linux kernel6.2 and later · before 6.6.158
linux linux kernel6.7 and later · before 6.12.111
linux linux kernel6.13 and later · before 6.18.53
linux linux kernel6.19 and later · before 7.2.7
linux linux kernel2.6.12
linux linux kernel7.3

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.190-1	6.1.190-1
Debian:12	linux-6.12	before 6.12.111-1~deb12u1	6.12.111-1~deb12u1
Debian:13	linux	before 6.12.111-1	6.12.111-1
Debian:14	linux	before 7.2.7-1	7.2.7-1

Same product

linux: all records

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Published before and after this one in the same product

← EarlierCVE-2026-98121Sep 25, 2026 · watchdog: msc313e: Fix NULL pointer dereference in PM callbacks
22Monitor
← EarlierCVE-2026-98122Sep 25, 2026 · vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()
31Monitor
Later →CVE-2026-98124Sep 25, 2026 · smb/client: invalidate fscache for fallocate range operations
22Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
Linux Linux	2cb0b0b1ed69430bf73740377ea0a1c44c50db63	Vendor (CNA)
Linux Linux	3be02999ab9131a4b96eb1eda4ca48b1cea80f03	Vendor (CNA)
Linux Linux	4548d843e7b29f6d150d8caae4e64015fa226b0c	Vendor (CNA)
Linux Linux	5fbc6a778d5fce7628821236972596acb18e1065	Vendor (CNA)
Linux Linux	7ba84e2971d208a2d6413a334ec28a8a32cdce0f	Vendor (CNA)
Linux Linux	7d8e7ab6a0665888beee91f7ad77ac805963c4fd	Vendor (CNA)
Linux Linux	abf59d7f6fff23227256e8199aca5ade45758f8b	Vendor (CNA)
Linux Linux	ba54cad229977f4fae6355dbdaf117088414fdd0	Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0	6.6.158.1-1 · Release Notes	Microsoft (MSRC)
debian:linux	6.1.190-1 · Debian:12	Package registry (OSV)
debian:linux	6.12.111-1 · Debian:13	Package registry (OSV)
debian:linux-6.12	6.12.111-1~deb12u1 · Debian:12	Package 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.