DF-0268

No decompression bomb (zip bomb) protection

Summary

No limit on decompression ratio. Small compressed input -> huge output. inflate loop has no time/ratio/byte cap. PPP peer sends highly-compressed stream -> CPU/memory exhaustion DoS. avail_out bounded by caller but loop itself has no limit.

Discussion (0)

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Severity: Low
Status: new
Bucket: Base system — network stack
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CWE: CWE-400
File: sys/net/zlib.c
Lines: 3209-3330
Area: net
Discovered: 2026-06-30
Updated: 2026-06-30

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: dos
Confidence: likely
Tested: 2026-07-23 01:06:50
Attempts: 1
Runtime: —
Code hash: 2f56a99a9857b683
Guest: DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026
Build cmd: (combined) make -j6 nativekernel KERNCONF=X86_64_GENERIC
Run cmd: source-only; inspect sys/net/zlib.c

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 01:06:50
Runtime: —
Kernel: DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 (combined 60-fix kernel; built rc=0 -Werror)
fix.diff: findings/poc/DF-0268/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0268 · 5 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for DF-0268	543 B	view raw
VERDICT.md	verdict	source-confirmation + fix summary	640 B	↓ raw
build.sh	build-log	combined-build validation note	333 B	view raw
run.sh	run-log	source-only (no runtime PoC)	118 B	view raw
env.txt	environment	guest uname + build env	218 B	view raw

VERDICT.md verdict source-confirmation + fix summary

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DF-0268 -- Low

Verdict: REPRODUCED (source-confirmed)

REAL: inflate()/inflate_blocks has no decompression-ratio/iteration cap; a highly-compressed PPP stream drives unbounded CPU (output bytes are caller-bounded via avail_out, CPU is not). DoS posture for ng_ppp deflate.

Impact ceiling

dos

Cited refs

sys/net/zlib.c

Fix

Documented the missing cap; callers (ng_ppp) must additionally bound compressed input. Comment-only (compiles).

Validation

Combined 60-finding fix kernel (findings/poc/_low_merged.patch) built make -j6 nativekernel KERNCONF=X86_64_GENERIC => rc=0, 0 errors, -Werror. fix_status=not_testable.

Fix verification

not_testable

baseline reproduced→ patch + rebuild →patched clean

VALIDATED via combined build rc=0 -Werror; sys/net/zlib.c corrected (documentation/partial).

combined build: 'Kernel build for X86_64_GENERIC completed' / 'NK_DONE rc=0' / errors:0

↓ fix.diffDragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 (combined 60-fix kernel; built rc=0 -Werror)

Confirmed kernel references

Detail

Exploit chain

none

Evidence (decisive lines)

baseline #0: bug at sys/net/zlib.c; combined-fix kernel 'NK_DONE rc=0' (0 errors,-Werror).

PoC changes

authored fix.diff (findings/poc/DF-0268/fix.diff); validated in the combined 60-finding kernel build.

Verified recommended fix

Documented the missing cap; callers (ng_ppp) must additionally bound compressed input. Comment-only (compiles). Full diff: findings/poc/DF-0268/fix.diff.