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TI-2026-45451 Aliases CVE-2026-63886GHSA-f9cg-2c9v-xhmh

scsi: target: iscsi: Validate CHAP_R length before base64 decode

Priority MEDIUM 50CWE-122Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 32 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-122 and the CVSS impact.

Summary

In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Validate CHAP_R length before base64 decode chap_server_compute_hash() allocates client_digest as kzalloc(chap->digest_size) and then, for BASE64-encoded responses, passes chap_r directly to chap_base64_decode() without checking whether the input length could produce more than digest_size bytes of output. chap_base64_decode() writes to the destination unconditionally as long as there is input to consume. With MAX_RESPONSE_LENGTH set to 128 and the "0b" prefix stripped by extract_param(), up to 127 base64 characters can reach the decoder. 127 characters decode to 95 bytes. For SHA-256 (digest_size=32) this overflows client_digest by 63 bytes; for MD5 (digest_size=16) the overflow is 79 bytes. The length check at line 344 fires after the write has already happened. The HEX branch in the same switch statement already validates the length up front. Apply the same approach to the BASE64 branch: strip trailing base64 padding characters, then reject any input whose data length exceeds DIV_ROUND_UP(digest_size * 4, 3) before calling the decoder. Stripping trailing '=' before the comparison handles both padded and unpadded encodings. chap_base64_decode() already returns early on '=', so the full original string is still passed to the decoder unchanged. The mutual CHAP path decodes CHAP_C into initiatorchg_binhex, which is kzalloc(CHAP_CHALLENGE_STR_LEN). extract_param() caps initiatorchg at CHAP_CHALLENGE_STR_LEN characters, so at most CHAP_CHALLENGE_STR_LEN-1 base64 characters reach the decoder. The maximum decoded size, DIV_ROUND_UP((CHAP_CHALLENGE_STR_LEN-1) * 3, 4), is less than CHAP_CHALLENGE_STR_LEN, so no overflow is possible there. A comment is added at the call site to document this.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00711 53rd percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.176, 6.6.143, 6.12.93 +3Red Hat: 9 advisoriesRed Hat: 32 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.0 and later6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1Patch availableCNA
  • Linux VendorLinux Affected 6.0 and later Fixed in 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1 Patch available CNA

CPE configurations NVD · 6

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*6.0 to before 6.1.176; 6.2 to before 6.6.143; 6.7 to before 6.12.93; 6.13 to before 6.18.35; 6.19 to before 7.0.12VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*7.1 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*7.1 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*7.1 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*7.1 rc4VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*7.1 rc5VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.0 to before 6.1.176; 6.2 to before 6.6.143; 6.7 to before 6.12.93; 6.13 to before 6.18.35; 6.19 to before 7.0.12 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* Versions 7.1 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* Versions 7.1 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* Versions 7.1 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* Versions 7.1 rc4 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* Versions 7.1 rc5 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1

Red Hat 9 advisories

  • RHSA-2026:67723 Released 2026-09-16 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) kernel-64k-debug-devel-5.14.0-284.191.1.el9_2, kernel-64k-debug-devel-matched-5.14.0-284.191.1.el9_2, kernel-64k-devel-5.14.0-284.191.1.el9_2 +10
    • Red Hat Enterprise Linux BaseOS E4S (v.9.2) bpftool-7.0.0-284.191.1.el9_2, kernel-5.14.0-284.191.1.el9_2, kernel-64k-5.14.0-284.191.1.el9_2 +29
  • RHSA-2026:67721 Released 2026-09-16 · Red Hat rating Important
    kernel-rt security, bug fix, and enhancement update
    • Red Hat Enterprise Linux Real Time E4S (v.9.2) kernel-rt-5.14.0-284.191.1.rt14.476.el9_2, kernel-rt-core-5.14.0-284.191.1.rt14.476.el9_2, kernel-rt-debug-5.14.0-284.191.1.rt14.476.el9_2 +9
    • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2) kernel-rt-5.14.0-284.191.1.rt14.476.el9_2, kernel-rt-core-5.14.0-284.191.1.rt14.476.el9_2, kernel-rt-debug-5.14.0-284.191.1.rt14.476.el9_2 +11
  • RHSA-2026:65708 Released 2026-09-09 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) kernel-tools-libs-devel-5.14.0-570.140.1.el9_6, libperf-5.14.0-570.140.1.el9_6
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) kernel-64k-debug-devel-5.14.0-570.140.1.el9_6, kernel-64k-debug-devel-matched-5.14.0-570.140.1.el9_6, kernel-64k-devel-5.14.0-570.140.1.el9_6 +12
    • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel-5.14.0-570.140.1.el9_6, kernel-64k-5.14.0-570.140.1.el9_6, kernel-64k-core-5.14.0-570.140.1.el9_6 +28
    • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt-5.14.0-570.140.1.el9_6, kernel-rt-64k-5.14.0-570.140.1.el9_6, kernel-rt-64k-core-5.14.0-570.140.1.el9_6 +21
    • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt-5.14.0-570.140.1.el9_6, kernel-rt-core-5.14.0-570.140.1.el9_6, kernel-rt-debug-5.14.0-570.140.1.el9_6 +11
Show 6 more Red Hat advisories
  • RHSA-2026:65712 Released 2026-09-09 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream E4S (v.9.4) kernel-64k-debug-devel-5.14.0-427.149.1.el9_4, kernel-64k-debug-devel-matched-5.14.0-427.149.1.el9_4, kernel-64k-devel-5.14.0-427.149.1.el9_4 +11
    • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool-7.3.0-427.149.1.el9_4, kernel-5.14.0-427.149.1.el9_4, kernel-64k-5.14.0-427.149.1.el9_4 +29
    • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt-5.14.0-427.149.1.el9_4, kernel-rt-core-5.14.0-427.149.1.el9_4, kernel-rt-debug-5.14.0-427.149.1.el9_4 +9
    • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt-5.14.0-427.149.1.el9_4, kernel-rt-core-5.14.0-427.149.1.el9_4, kernel-rt-debug-5.14.0-427.149.1.el9_4 +11
  • RHSA-2026:64767 Released 2026-09-08 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) kernel-64k-debug-devel-6.12.0-55.103.1.el10_0, kernel-64k-debug-devel-matched-6.12.0-55.103.1.el10_0, kernel-64k-devel-6.12.0-55.103.1.el10_0 +12
    • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel-6.12.0-55.103.1.el10_0, kernel-64k-6.12.0-55.103.1.el10_0, kernel-64k-core-6.12.0-55.103.1.el10_0 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) kernel-tools-libs-devel-6.12.0-55.103.1.el10_0, libperf-6.12.0-55.103.1.el10_0
    • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt-6.12.0-55.103.1.el10_0, kernel-rt-64k-6.12.0-55.103.1.el10_0, kernel-rt-64k-core-6.12.0-55.103.1.el10_0 +21
    • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt-6.12.0-55.103.1.el10_0, kernel-rt-core-6.12.0-55.103.1.el10_0, kernel-rt-debug-6.12.0-55.103.1.el10_0 +11
  • RHSA-2026:63129 Released 2026-09-04 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.44.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.44.1.el9_8, kernel-64k-devel-5.14.0-687.44.1.el9_8 +12
    • Red Hat Enterprise Linux BaseOS (v. 9) kernel-5.14.0-687.44.1.el9_8, kernel-64k-5.14.0-687.44.1.el9_8, kernel-64k-core-5.14.0-687.44.1.el9_8 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.44.1.el9_8, libperf-5.14.0-687.44.1.el9_8
    • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-687.44.1.el9_8, kernel-rt-64k-5.14.0-687.44.1.el9_8, kernel-rt-64k-core-5.14.0-687.44.1.el9_8 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-687.44.1.el9_8, kernel-rt-core-5.14.0-687.44.1.el9_8, kernel-rt-debug-5.14.0-687.44.1.el9_8 +9
  • RHSA-2026:59821 Released 2026-08-26 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.158.1.el8_10, kernel-4.18.0-553.158.1.el8_10, kernel-abi-stablelists-4.18.0-553.158.1.el8_10 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.158.1.el8_10
  • RHSA-2026:59737 Released 2026-08-26 · Red Hat rating Important
    kernel-rt security, bug fix, and enhancement update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.158.1.rt7.499.el8_10, kernel-rt-core-4.18.0-553.158.1.rt7.499.el8_10, kernel-rt-debug-4.18.0-553.158.1.rt7.499.el8_10 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.158.1.rt7.499.el8_10, kernel-rt-core-4.18.0-553.158.1.rt7.499.el8_10, kernel-rt-debug-4.18.0-553.158.1.rt7.499.el8_10 +7
  • RHSA-2026:57251 Released 2026-08-20 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.49.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.49.1.el10_2, kernel-64k-devel-6.12.0-211.49.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.49.1.el10_2, kernel-64k-6.12.0-211.49.1.el10_2, kernel-64k-core-6.12.0-211.49.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.49.1.el10_2, libperf-6.12.0-211.49.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.49.1.el10_2, kernel-rt-64k-6.12.0-211.49.1.el10_2, kernel-rt-64k-core-6.12.0-211.49.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.49.1.el10_2, kernel-rt-core-6.12.0-211.49.1.el10_2, kernel-rt-debug-6.12.0-211.49.1.el10_2 +9

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 9AffectedNo fix yet
Red Hat CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2026:65708
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:57251
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:63129
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:67723
Red Hat Enterprise Linux AppStream E4S (v.9.4)Fixed RHSA-2026:65712
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:64767
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:65708
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:57251
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2026:59821
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2026:63129
Red Hat Enterprise Linux BaseOS E4S (v.9.2)Fixed RHSA-2026:67723
Red Hat Enterprise Linux BaseOS E4S (v.9.4)Fixed RHSA-2026:65712
Red Hat Enterprise Linux BaseOS EUS (v. 10.0)Fixed RHSA-2026:64767
Red Hat Enterprise Linux BaseOS EUS (v.9.6)Fixed RHSA-2026:65708
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:59821
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:57251
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:63129
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)Fixed RHSA-2026:64767
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2026:59737
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2026:59737
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:57251
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2026:63129
Red Hat Enterprise Linux Real Time E4S (v.9.2)Fixed RHSA-2026:67721
Red Hat Enterprise Linux Real Time E4S (v.9.4)Fixed RHSA-2026:65712
Red Hat Enterprise Linux Real Time EUS (v. 10.0)Fixed RHSA-2026:64767
Red Hat Enterprise Linux Real Time EUS (v.9.6)Fixed RHSA-2026:65708
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:57251
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2026:63129
Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)Fixed RHSA-2026:67721
Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4)Fixed RHSA-2026:65712
Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)Fixed RHSA-2026:64767
Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6)Fixed RHSA-2026:65708
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-63886
  2. 2026-10-03 Alias added: GHSA-f9cg-2c9v-xhmh
  3. 2026-10-13 Affected versions changed · Red Hat
  4. 2026-10-16 CISA SSVC decision points changed
  5. 2026-10-19 Weakness changed · CISA ADP
  6. 2026-10-23 Weakness changed · NVD

References

Patch 6

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences