Linux Kernel up to 6.12.108/6.18.49/7.2.3 SUNRPC svcauth_gss_unwrap_priv len divide by zero

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6.2	$0-$5k	0.00+

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. Affected is the function svcauth_gss_unwrap_priv of the component SUNRPC. Performing a manipulation of the argument len results in divide by zero. This vulnerability was named CVE-2026-89550. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. This affects the function svcauth_gss_unwrap_priv of the component SUNRPC. The manipulation of the argument len with an unknown input leads to a divide by zero vulnerability. CWE is classifying the issue as CWE-369. The product divides a value by zero. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: svcauth_gss: enforce krb5 token minimum length svcauth_gss_unwrap_priv() validates only an upper bound on the wire-supplied opaque length before handing the buffer to gss_unwrap(): if (len > xdr_stream_remaining(xdr)) goto unwrap_failed; offset = xdr_stream_pos(xdr); ... maj_stat = gss_unwrap(ctx, offset, offset + len, buf); The wire value `len` flows unchanged as the upper bound into the krb5 unwrap path, so a len in [0, 16] passes this check and is handed to gss_unwrap(). For a krb5 v2 context that lands in gss_krb5_unwrap_v2(), which reads the 16-byte RFC 4121 token header fields at ptr+4 and ptr+6 and then calls rotate_left() before any integrity check. With a sub-header length the header reads run past the token, and _rotate_left()'s `shift %= buf->len` path can divide by zero when buf->len has been driven to zero by the truncated token. A header-only token (len == 16) is equally invalid: with a non-zero RRC field and the opaque blob ending at the XDR buffer boundary, rotate_left() builds a zero-length subbuffer, reaching the same division. Reject the token at the server entry point before it reaches the krb5 unwrap core. A valid sealed RFC 4121 token must contain the 16-byte header plus at least some encrypted payload. Fix by adding a minimum-length check immediately after the existing upper-bound check: if (len <= GSS_KRB5_TOK_HDR_LEN) goto unwrap_failed;

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-89550 since 09/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/12/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch dd6afc6cab8c5d387d1ed2f069562ef7bdadd651/de942dd8c2c8358bcad04ce44271954c48924423/2eed1e6a976a44015c3ee78841fe336796e2b21c/a919c5c88769cf8fb3ec071e6078d830bf512489 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.108
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Divide by zero
CWE: CWE-369 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: dd6afc6cab8c5d387d1ed2f069562ef7bdadd651/de942dd8c2c8358bcad04ce44271954c48924423/2eed1e6a976a44015c3ee78841fe336796e2b21c/a919c5c88769cf8fb3ec071e6078d830bf512489

Timelineinfo

09/11/2026 CVE reserved
09/11/2026 +0 days VulDB entry created
09/12/2026 +0 days Advisory disclosed
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89550 (🔒)
GCVE (CVE): GCVE-0-2026-89550
GCVE (VulDB): GCVE-100-402753

Entryinfo

Created: 09/12/2026 00:16
Changes: 09/12/2026 00:16 (60)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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