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CVE-2026-11850— Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds read

Quick assessment

Affected
Red Hat Red Hat Hardened Images
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MIT krb5（MIT Kerberos 5）是美国麻省理工（Massachusetts Institute Of Technology）大学的一套网络认证协议，它采用客户端/服务器结构，并且客户端和服务器端均可对对方进行身份认证（即双重验证），可防止窃听、防止replay攻击等。 MIT krb5存在数字错误漏洞，该漏洞源于berval2tl_data()函数中整数下溢，未进行边界检查的无符号减法导致后续malloc成功并读取超出缓冲区数据，可能导致堆越界读取。

CVSS 5.0 · Medium EPSS 0.26% · P18

Affected Version Matrix 7

VendorProduct Version RangeStatus
Red Hat Red Hat Enterprise Linux 10 any affected
Red Hat Red Hat Enterprise Linux 6 any affected
Red Hat Red Hat Enterprise Linux 7 any affected
Red Hat Red Hat Enterprise Linux 8 any affected
Red Hat Red Hat Enterprise Linux 9 any affected
Red Hat Red Hat Hardened Images 1.22.2-8.hum1< * unaffected
Red Hat Red Hat OpenShift Container Platform 4 any affected
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I. Basic Information for CVE-2026-11850

Vulnerability Information
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Vulnerability Title
Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds read
Source: CVE Program / CVE List V5
Vulnerability Description
An integer underflow vulnerability was found in MIT krb5 in the berval2tl_data() function in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c. The function performs an unsigned subtraction (bv_len - 2) without a prior bounds check. When bv_len is 0 or 1, the subtraction wraps to a large value which is then truncated to uint16_t, yielding 0xFFFE (65534) or 0xFFFF (65535). The subsequent malloc succeeds and memcpy reads up to 65534 bytes from a 0-1 byte buffer, resulting in a heap out-of-bounds read. The attack vector involves a malicious or compromised LDAP KDB backend returning a krbExtraData attribute with bv_len < 2, triggering the underflow when the KDC or kadmind reads principal data.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Vulnerability Title
MIT krb5 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MIT krb5（MIT Kerberos 5）是美国麻省理工（Massachusetts Institute Of Technology）大学的一套网络认证协议，它采用客户端/服务器结构，并且客户端和服务器端均可对对方进行身份认证（即双重验证），可防止窃听、防止replay攻击等。 MIT krb5存在数字错误漏洞，该漏洞源于berval2tl_data()函数中整数下溢，未进行边界检查的无符号减法导致后续malloc成功并读取超出缓冲区数据，可能导致堆越界读取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat Hardened Images 1.22.2-8.hum1 ~ * cpe:/a:redhat:hummingbird:1
Red Hat Red Hat Enterprise Linux 10 - cpe:/o:redhat:enterprise_linux:10
Red Hat Red Hat Enterprise Linux 6 - cpe:/o:redhat:enterprise_linux:6
Red Hat Red Hat Enterprise Linux 7 - cpe:/o:redhat:enterprise_linux:7
Red Hat Red Hat Enterprise Linux 8 - cpe:/o:redhat:enterprise_linux:8
Red Hat Red Hat Enterprise Linux 9 - cpe:/o:redhat:enterprise_linux:9
Red Hat Red Hat OpenShift Container Platform 4 - cpe:/a:redhat:openshift:4

II. Public POCs for CVE-2026-11850

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III. Intelligence Information for CVE-2026-11850

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Vendor Advisories for CVE-2026-11850 (3)

Same Patch Batch · Red Hat · 2026-06-11 · 5 CVEs total

CVE-2026-11774 7.6 HIGH 389-ds-base: 389-ds-base: integer overflow in sasl packet length bypasses size limit leadi
CVE-2026-53701 6.5 MEDIUM Gstreamer1-plugins-bad-free: gstreamer: out-of-bounds write in h.266/vvc pps picture parti
CVE-2026-53702 6.5 MEDIUM Gstreamer1-plugins-bad-free: gstreamer: stack buffer overflow in h.265 buffering period se
CVE-2026-11986 4.9 MEDIUM Keycloak-rest-admin-ui-ext: authorization bypass vulnerability in the admin-ui-ext bulk ro

IV. Related Vulnerabilities

Same product: Red Hat Hardened Images
Same vendor: Red Hat
Same weakness: CWE-191

V. Comments for CVE-2026-11850

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