# CVE-2026-64317: isofs: bound Rock Ridge symlink components to the SL record

Status: published. Published: 2026-07-25. Updated: 2026-11-10.

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

isofs: bound Rock Ridge symlink components to the SL record

get_symlink_chunk() and the SL handling in
parse_rock_ridge_inode_internal() walk the variable-length components of
a Rock Ridge "SL" (symbolic link) record.  Each component is a two-byte
header (flags, len) followed by len bytes of text, so it occupies
slp->len + 2 bytes.  Both loops read slp->len and advance to the next
component, and get_symlink_chunk() additionally does
memcpy(rpnt, slp->text, slp->len), but neither checks that the component
lies within the SL record before dereferencing it.

A crafted SL record whose component declares a len that runs past the
record (rr->len) therefore triggers an out-of-bounds read of up to 255
bytes.  When the record sits at the tail of its backing buffer - for
example a small kmalloc()ed continuation block reached through a CE
record - the read crosses the allocation; get_symlink_chunk() then
copies the out-of-bounds bytes into the symlink body returned to user
space by readlink(), disclosing adjacent kernel memory.

ISO 9660 images are routinely mounted from untrusted removable media -
desktop environments auto-mount them (e.g. via udisks2) without
CAP_SYS_ADMIN - so the record contents are attacker-controlled.

Reject any component that does not fit in the remaining record bytes
before using it.  In get_symlink_chunk() return NULL, like the existing
output-buffer (plimit) checks, so a malformed record makes readlink()
fail with -EIO rather than silently returning a truncated target; in
parse_rock_ridge_inode_internal() stop the inode-size walk.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 1015e1c4b2fadd9c09704e24738e46598778c869 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 36fe7d25dbc40da0c6b1dd4513a4f69ac6164eee (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < a22cb6bb54dc167047ea9e70d97dfbc2c15649e3 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < b736b12108fd116c41777628f5a333791604df26 (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 6bf41db09ef935d76fcc84ccf213b42c18de95ee (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < b5699642640d6cff357638738c5293985cd5a53d (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 9830725078c8483c6831ec10222ae724806ea36b (affected, git); ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 5fa1d6a5ec2356d2107dead614437c66fa7138b1 (affected, git). Source: CNA: Linux
- Linux / Linux: 2.6.12 (affected); ≥ 0; < 2.6.12 (unaffected, semver); ≥ 5.10.261; ≤ 5.10.* (unaffected, semver); ≥ 5.15.212; ≤ 5.15.* (unaffected, semver); ≥ 6.1.178; ≤ 6.1.* (unaffected, semver); ≥ 6.6.145; ≤ 6.6.* (unaffected, semver); ≥ 6.12.96; ≤ 6.12.* (unaffected, semver); ≥ 6.18.39; ≤ 6.18.* (unaffected, semver); ≥ 7.1.4; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP

## Severity and prioritization

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H; source: CNA: Linux

- CISA KEV: No listing in collected sources

- EPSS: 0.17% as of 2026-11-09; percentile 6.62%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/1015e1c4b2fadd9c09704e24738e46598778c869 (CNA: Linux)

- https://git.kernel.org/stable/c/36fe7d25dbc40da0c6b1dd4513a4f69ac6164eee (CNA: Linux)

- https://git.kernel.org/stable/c/a22cb6bb54dc167047ea9e70d97dfbc2c15649e3 (CNA: Linux)

- https://git.kernel.org/stable/c/b736b12108fd116c41777628f5a333791604df26 (CNA: Linux)

- https://git.kernel.org/stable/c/6bf41db09ef935d76fcc84ccf213b42c18de95ee (CNA: Linux)

- https://git.kernel.org/stable/c/b5699642640d6cff357638738c5293985cd5a53d (CNA: Linux)

- https://git.kernel.org/stable/c/9830725078c8483c6831ec10222ae724806ea36b (CNA: Linux)

- https://git.kernel.org/stable/c/5fa1d6a5ec2356d2107dead614437c66fa7138b1 (CNA: Linux)

- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (ADP: siemens-SADP)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-64317; retrieved 2026-11-10; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-64317; retrieved 2026-11-10; source updated Not reported

Revision: 8d1ffad6fb2960f0bcb3bd167f75a284cf7b7fbbaeb2368cacc474ab1b5c5a3a

Canonical: https://y2.dev/cve/CVE-2026-64317

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